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The effects of fasting for a single day and during
Ramadan upon performance
By
Hadhom Mohamed Alabed
A thesis submitted in partial fulfilment of the requirements by Liverpool John Moores University for
the degree of Doctor of Philosophy
March 2010
Any pages, tables, figures or photographs, missing from this digital copy, have been excluded at the request of the university .
ACKNOWLEDGEMENTS
First and foremost, I am thankful to God the most Merciful for giving me the patience,
perseverance and courage to finish this work.
I would also like to express my gratitude to all who have directly or indirectly contributed to
this thesis. First, like I would to thank Professors Tim Cable, Tom Reilly and Keith George
for allowing me to work in the laboratories and use the facilities of the Institute. The death of
Tom Reilly saddened me greatly; may he rest in peace.
I would like to thank my supervisory team. I wish to express my special thanks and gratitude
to my main supervisor, Professor Jim Waterhouse (Professor of Biological Rhythms). Indeed,
he is an excellent example of a University tutor who cares about his students at a personal
level, and I have certainly learned much from him. He has been a constant source of advice.
Without his invaluable advice, guidance, positive attitude and encouraging remarks, this
thesis could not have been written. I appreciate this opportunity to work with and alongside
him.
I would like to express my deepest gratitude and appreciation also to my second supervisor,
Dr. Ben Edwards (Senior Lecturer), for his continual assistance and helpful collaboration in
the development, performance and writing up of this thesis.
I also extend my gratitude to all the participants of this study who gave up their time to
participate in the project. Without them, the research would not have been possible. I also
thank the laboratory staff at Liverpool John Moores University for their contributions and
help.
I express my profound gratitude to my parents, for their prayers and all the sacrifices they
have made for me. Many thanks to my brother for his emotional support, encouragement and
patience, and also to him and my sisters for their prayers. I offer them my heartfelt thanks and
owe them more than words can say. Their love, patience, understanding, support and,
especially, their great sacrifice allowed me to complete this research. Certainly, without them
this thesis would have never been possible. I am also personally indebted to them for their
constant interest, moral support and encouragement.
My thanks must also go to the many friends who have encouraged my work. Also my thanks
to coach Yosaf Al-shoshan, Awatef Abuswesha, souad al-jadeed and the participants from
Alahli, Tripoli who helped me in my field study in Libya. All of these have also made me feel
welcome and at home.
Finally, I am eternally grateful to the Libya Arab Jamahiriya who provided me with much
needed funds to undertake my research and PhD programme in the UK.
Abstract
Abstract
Ramadan requires individuals to abstain from food and fluid intake between sunrise and
sunset; physiological considerations predict that poorer mood, physical performance and
mental performance will result. In addition, any difficulties will be worsened because
preparations for fasting and recovery from it often mean that nocturnal sleep is decreased in
length, and this independently affects mood and performance.
Previous field studies have indicated that some of these predictions are borne out in practice;
in the first study of the present thesis, a field study performed in Libya, these predictions
were tested further by adding more physiological measurements and tests of performance.
Findings indicated that Ramadan was associated with negative effects upon a wide range of
variables, including rising urine daytime osmolality (indicative of progressive dehydration),
SUbjective estimates of amounts of activities actually performed and those wished to be done
(indicating less activity in the daytime), and metabolic and subjective responses to a short
bout of exercise (increased effort required and metabolism tending towards fat rather than
glucose catabolism).
Because of the difficulties of performing a battery of tasks in a field study, two laboratory
based experiments were then performed, the second differing from the first in studying a
greater range of variables and more time-points during the daytime. These two studies also
differed from the situation in Ramadan in that non-Muslim students were volunteers and
fasting was performed for only one day. Many of the changes previously found in Ramadan
were duplicated in this work, so justifying the use of laboratory experiments lasting one day
and using non-Muslim subjects as a model for some of the problems present in Ramadan.
v
However, it was also found that preparations before the fast were often less marked than was
the case with Muslims in Ramadan, a difference that can be attributed to subjects' lack of
experience of fasting as well as the amount of time spent fasting.
A difficulty of interpretation in all these studies was that changes could be due to fasting
and/or the length of sleep, which tends to decrease. These two factors were separated in the
final experiment, an intervention study performed in the laboratory. This study compared
effects of different durations of fasting (4, 8 or 16 h) upon a wide variety of measures
(including subjective and objective assessments of performance, dehydration and responses
to a short bout of exercise) - but with an unchanged amount of nocturnal sleep and daytime
naps not allowed. Many of the negative effects observed in previous studies were present in
this experiment also. These findings indicate that fasting was responsible for much of the
change previously observed, though some effect of sleep loss, particularly if occurring on
successive days (as would occur in Ramadan) cannot be excluded.
One finding common to all studies was that tests of performance that had shown variations
due to the combination of circadian influences, time awake and sleep loss in other
experiments (including grip strength, the Stroop test and accuracy at throwing darts) seemed
little affected. Possible reasons for these negative findings are discussed, together with further
experiments to separate out effects of sleep loss and fasting, and the role of subjects'
experience in studies of fasting. In addition, more detailed studies to investigate changes in
sleep and the type and level of physical activities when fasting are proposed.
VI
Contents
Table of Contents
The effects of fasting for a single day and during Ramadan upon performance
ACKNOWLEDGEMENTS
Abstract
Chapterl
I. A Brief Outline of the Thesis
II. An Introduction to Ramadan and Factors Influencing Normal Food Intake
I.A Brief Outline of the Thesis ............................................................................. 2
II. An Introduction to Ramadan and Factors Affecting Normal Food Intake ...... 6
1.1. The Timing of Ramadan ............................................................................................. 6
1.2. The Requirements of Ramadan ................................................................................... 7
1.3. Effects of Changed Eating Habits in Ramadan ........................................................... 8
1.3.1. Normal eating habits ........................................................................................ 8
1.3.2. Effects of time of meal upon total daily intake ................................................ 9
1.3.3. Factors affecting food intake ......................................................................................... 9
1.3.3.1. Cultural ......................................................................................................... 9
1.3.3.2. Social factors and time availability ............................................................. 10
104. The Body Clock and Circadian Rhythms ....................................................................... 10
1.4.1. The role of the body clock ............................................................................. 11
1.4.2. The role ofthe body clock in regulating food intake ..................................... 13
Chapter 2
The Demands and Effects of Ramadan:Review of the Literature
2.1. Effects of Ramadan upon Body Weight, Metabolism and Sleep ................................... 16
2.1.1. Body weight, fluid intake and water content ................................................. 17
2.1.2. Food intake and metabolism .......................................................................... 18
2.1.3. Sleep ............................................................................................................... 21
2.2. Ramadan and Physical and Mental Performance, Mood and Social Activity .................. 22
2.2.1. Mental performance and fatigue .................................................................... 23
2.2.2. Physical performance ..................................................................................... 25
2.3. Clinical Implications of Ramadan .................................................................................. 28
204. Changes During the Course of the Day .......................................................................... 28
2.5. Aims and Objectives of the Experiments to be performed ............................................. 31
VIII
Chapter 3
Effects of Ramadan upon Physical Activity: a Field Study
3.1. Introduction .................................................................................................................... 34
3.2. Methods .......................................................................................................................... 35
3.2.1. Subjects and familiarisation ..................................................................................... 35
3.2.2. Protocol and measurements ...................................................................................... 36
3.2.2.1. Questionnaires ............................................................................................. 37
3.2.2.2. Physiological measures ............................................................................... 39
3.2.3. Statistics ......................................................................................................................... 41
3.3. Results ............................................................................................................................ 41
3.3.1. Results from questionnaires ........................................................................................... 41
3.3.1.1. Nocturnal sleep ........................................................................................... 41
3.3.1.2. Diurnal naps ................................................................................................ 42
3.3.1.3. Fluid and food intake .................................................................................. 43
3.3.1.4. Subjective estimates of activities and sleepiness ........................................ 46
3.3.2. Urine osmolality ............................................................................................................. 47
3.3.3. Physical performance measures ..................................................................................... 47
3.4. Discussion ....................................................................................................................... 54
3.5. Conclusions and Limitations .......................................................................................... 58
3.5.1. Limitations of the study ................................................................................. 59
Chapter 4
Laboratory-based studies.
I.Introduction to Laboratory-based Studies
II.A Pilot Study of Changes in Body Mass and Physical Performance During One Day of Fasting
I. Introduction to Laboratory-based Studies .......................................................................... 62
4.1 Advantages and disadvantages of field- and laboratory-based studies ....................... 63
4.2 Rational for the three laboratory-based studies ........................................................... 64
II. A Pilot Study of changes in Body Mass and Physical Performance during One Day of Fasting .................................................................................................................................. 66
4.3. Methods .......................................................................................................................... 66
4.3.1. Subjects .................................................................................................................. 66
4.3.2. General design ....................................................................................................... 67
4.3.3. Measurements made ............................................................................................... 68
4.3.3.1. Body mass ................................................................................................... 68
4.3.3.2. Physiological Variables .............................................................................. 68
4.3.4. Statistics ......................................................................................................................... 69
IX
4.4. Results ............................................................................................................................ 69
4.4.1. Body Mass ............................................................................................................... 69
4.4.2. Urine osmolality ....................................................................................................... 70
4.4.3. Grip strength ............................................................................................................. 71
4.4.4. Exercise ..................................................................................................................... 72
4.5. Discussion ....................................................................................................................... 73
Chapter 5
A More Detailed Study of Changes in Performance Produced by One Day of Fasting
5.1. Rationale ......................................................................................................................... 76
5.2. Methods .......................................................................................................................... 77
5.2.1. Subjects .......................................................................................................... 77
5.2.2. Protocol .......................................................................................................... 77
5.2.3. Measurements made ....................................................................................................... 79
5.2.3.1. Questionnaires ............................................................................................. 79
5.2.3.2. Physiological and performance tests ........................................................................ 80
A. Urine osmolality .................................................................................................. 80
B. Stroop test ............................................................................................................ 80
C. Throwing darts .................................................................................................... 81
D. Hand grip strength ............................................................................................... 81
E. Jump height ......................................................................................................... 82
5.2.4. Statistical analysis .......................................................................................................... 82
5.3. Results ............................................................................................................................ 83
5.3.1. Results from questionnaires ........................................................................................... 83
5.3.1.1. Drinking ...................................................................................................... 83
5.3.1.2. Eating .......................................................................................................... 86
5.3.1.3. Physical activity .......................................................................................... 88
5.3.1.4. Mental activity ............................................................................................ 88
5.3.1.5. Social activity .............................................................................................. 89
5.3.1.6. Fatigue ......................................................................................................... 90
5.3.1. 7. Amount of physical activity wished for ...................................................... 90
5.3.1.8. Amount of mental activity Wished for ....................................................... 91
5.3.2. Urine osmolality ............................................................................................................. 92
5.3.3 Physical and mental performance ................................................................................... 92
5.3.3.1. Hand grip strength ....................................................................................... 92
5.3.3.2. Stroop test ................................................................................................... 93
5.3.3.3. Jump height ................................................................................................. 94
5.3.3.4. Throwing darts ............................................................................................ 94
x
5.3.4. Correlations between the variables ................................................................................ 97
5.4. Discussion ....................................................................................................................... 99
5.4.1. General conclusions ..................................................................................................... 104
5.4.1.1. Effects of fasting ....................................................................................... 104
5.4.1.2. Relationship between field and laboratory-based studies ......................... 105
5.4.1.3. Measurement tools .................................................................................... 1 05
5.4.1.4. Problems in these types of study ............................................................... 106
Chapter 6
An Intervention Study with Controlled Time for Sleep and Variable Length of Fasting
6.1. Introduction .................................................................................................................. 109
6.2. Methods ..................................................................................................................... 110
6.2.1. Subjects ........................................................................................................ 110
6.6.2. Protocol ........................................................................................................ 11 0
6.2.3. Measurements and apparatus ....................................................................................... 111
6.2.3.1. Actimetry .................................................................................................. 111
6.2.3.2. Questionnaires ........................................................................................... 112
6.2.3.3. Body mass and urine osmolality ............................................................... 112
6.2.3.4. Performance measures - throwing darts .................................................... 112
6.2.3.5. Exercise ..................................................................................................... 113
6.2.4. Treatment of results ..................................................................................................... 113
6.2.4.1. Questionnaires ........................................................................................... 113
6.2.4.2. Actimetry .................................................................................................. 114
6.2.4.3. Darts .......................................................................................................... 114
6.2.5. Statistics ..................................................................................................................... 114
6.3. Results .......................................................................................................................... 115
6.3.1. Questionnaires ........................................................................................................... 115
6.3.1.1. Sleep times and food and fluid intakes ..................................................... 115
6.3.1.2. Activities performed ................................................................................. 115
6.3.1.3. Activities wished for ................................................................................. 118
6.3.1.4. Perceived sleepiness .................................................................................. 119
6.3.2. Urine osmolality ........................................................................................................ 120
6.3.3. Actimetry ................................................................................................................... 120
6.3.4. Objective measures of performance - throwing darts ................................................ 121
6.3.5. Changes produced by exercise .................................................................................. 123
6.3.5.1. Body mass ................................................................................................. 123
6.3.5.2. Respiratory exchange ratio (RER) ............................................................ 123
6.3.5.3. Lactate ....................................................................................................... 124
XI
6.3.5.4. Heart rate ................................................................................................... 125
6.3.5.5. Rating of perceived exertion (RPE) .......................................................... 126
6.4. Discussion and Conclusions ......................................................................................... 127
6.4.1. Conclusions .................................................................................................. 132
Chapter 7
General Discussion, Conclusions, Future Work and Implications
7.1. General Aims ................................................................................................................ 134
7.2. The Field Study ............................................................................................................... 135
7.3. The Laboratory-based Studies ........................................................................................ 136
7.3.1. Separating the effects of sleep loss from fasting - the intervention study ... 13 7
7.4. Further Work ................................................................................................................ 138
7.4.1. Measurement of performance ...................................................................................... 138
7.4.2. Subjective vs. objective measurements of activity ...................................................... 139
7.4.3. Role of naps ................................................................................................................. 139
7.4.4. Possible interaction between sleep loss and fasting ..................................................... 140
7.4.5. Subjects' experience .................................................................................................... 141
7.4.6. Metabolism .................................................................................................................. 141
7.5. Concluding Comments and Implications of the Findings ............................................ 142
7.5.1. Implications of the findings ......................................................................................... 143
ChapterS
References ........................................................................................................................... 146
Chapter 9
Appendices .......................................................................................................................... 165
XII
List of Figures
Figure 2.1. Changes from normal days in hunger, top, and amount of indigestion, bottom, in a group of 12 subjects who underwent a 25-h constant routine. Mean + SE shown. (From Waterhouse et al., 1999a) ............................................................................... 19
Figure 2.2. Mean (tSE) profiles of physical activity scores during Control days and Ramadan. (From Waterhouse et al., 2008b) .......................................................... 30
Figure 3.1. Reasons given for not napping in the evening (top) and in the daytime (bottom) . ............................................................................................................ 44
Figure 3.2. Top, type of drink taken in the evening on control days and during Ramadan. Bottom, reasons given for drinking ................................................................. 45
Figure 3.3. Reasons for eating in the evening on control days and during Ramadan ........ 46
Figure 3.4. Changes with time of day on control days and Ramadan in: top, Physical activity; middle, Social activity; bottom, Sleepiness ........................................................ 49
Figure 3.5. Urinary osmotic pressure (mosmll) during control days and Ramadan ........... 51
Figure 3.6. Grip strength in dominant and non-dominant hands on control days vs. Ramadan ................................................................................................ 51
Figure 3.7. Effects of exercise on rise of heart rate, HR, at two times of day on control days and during Ramadan ................................................................................... 52
Figure 3.8. Effects of exercise at two times of day on cadence (cycles/min) on control days and during Ramadan.......................................... ....................................... 52
Figure 3.9. Effects of exercise at two times of day on post-exercise lactate (mmol/l) on control days and during Ramadan ................................................................... 53
Figure 3.10. Effects of exercise at two times of day rating of perceived exertion (RPE) on control days and during Ramadan ....................................................................... 53
Figure 4.1. Body mass. Mean and SE ............................................................... 70
Figure 4.2. Urine osmolality. Mean and SE ........................................................ 70
Figure 4.3. Grip strength, left (non-dominant) hand. Mean and SE ............................ 71
Figure 4.4. Grip strength, right (dominant) hand. Mean and SE ................................ 72
Figure 4.5. Heart rate at the end of the 5-min cycling. Mean and SE .......................... 72
Figure 5.1. Number of subjects drinking/not drinking before 09:00 h .......................... 84
XIII
Figure 5.2. Reasons for drinking before sunrise ................................................... 85
Figure 5.3. Reasons for drinking after sunset. ....................................................... 85
Figure 5.4. Number of subjects eating Inot eating before 09:00 h ............................... 86
Figure 5.5. Reasons for eating before sunrise ....................................................... 87
Figure 5.6. Reasons for eating after sunset. ....................................................... 87
Figure 5.7. Effect of time of day upon physical activity score on control and fasting days. Mean + SE .............................................................................................. 88
Figure 5.8. Effect of time of day upon mental activity score on control and fasting days. Mean + SE ............................................................................................. 89
Figure 5.9. Effect of time of day upon social activity score on control and fasting days. Mean + SE ...................................................................................................... 89
Figure 5.10. Effect of time of day upon fatigue on control and fasting days. Mean + SE. .. 90
Figure 5.11. Effect of time of day upon the desire to perform physical work on control and fasting days. Mean + SE .............................................................................. 91
Figure 5.12. Effect of time of day upon the desire to perform mental activity on control and fasting days. Mean +SE .............................................................................. 91
Figure 5.13. Mean +SE of urine osmolality under non-fasting and fasting conditions.... 92
Figure 5.14. Maximum hand grip strength (dominant hand). Mean and SE .................. 93
Figure 5.15. Time taken to complete test. Mean and SE ......................................... 93
Figure 5.16. Maximum height jumped. Mean + SE ............................................... 94
Figure 5.17. Total scores for darts 4-17. Mean + SE ............................................. 95
Figure 5.18. Mean number of zeros scored. Mean + SE. ......................................... 95
Figure 5.19. Mean score per hit. Mean + SE ....................................................... 96
Figure 6.1. Fraction of possible occasions that different types of fluid were drunk during supper just before the Control, Breakfast and Fasting days ....................................... 116
Figure 6.2. Scores for (A) physical activity, (B) mental activity and (C) social activity during Control, Breakfast and Fasting days. Mean + SE ................................................. 117
Figure 6.3. The effects of time of day and condition (Control, Breakfast and Fasting) upon physical activity wished for. Mean + SE ............................................................ 118
XIV
Figure 6.4. The effects of time of day and condition (Control, Breakfast Only and Fasting) upon mental activity wished for. Mean + SE ...................................................... 119
Figure 6.5. The effects of time of day and condition upon perceived sleepiness. Mean + SE ......................................................................................................... 119
Figure 6.6. Urine osmolality during the daytime in the three experimental conditions. Mean + SE ........................................................................................................ 120
Figure 6.7. Effects of time of day and conditions upon summed activities. Mean + SE ..... 121
Figure 6.8. Total scores for darts 4-17 on control, breakfast only and fasting days at the 3 times of measurement. Mean + SE .................................................................. 122
Figure 6.9. Mean number of zeros scored. Mean + SE ........................................... 122
Figure 6.10. Fall in body weight produced by exercise. Mean + SE ............................ 123
Figure 6.11. Changes in RER produced by exercise. Mean +SE. ............................... 124
Figure 6.12. Lactate rise following exercise at different times of day and during Control, Breakfast only and Fasting days. Mean + SE. ..................................................... 124
Figure 6.13. Rise in HR produced by exercise at different times of day on Control, Breakfast only and Fasting days. Mean + SE .................................................................. 125
Figure 6.14. Rating of perceived exertion (RPE) after bout of exercise. Mean + SE ......... 126
xv
List of Tables
Table 3.1. Analysis of Variance ...................................................................... 50
Table 5.1. Correlations between the variables using the method of Bland and Altman (1995) .
................................................................................................... 98
XVI
List of Appendices
Appendix 3.1. Consent Form ................................................................................................. 166
Appendix 3.2. (l=..4- ~t:ilI~t..JI rW..tic. o~ 0~'i1 o.)l4:i....I) (Questionnaire given on rising) . ................................................................................................................................................ 167
.Appendix 3.3. ~t:ill ~t..JI J Ip ~ ~WI~t..JI ,Ip y!t. ~~I ~t..JI rW..tic. o~ (J~'il o.)l4:i....J "t.......... (Questionnaire given later in the daytime) ..................................................................... 170
Appendix 4.1. Questionnaire given at 09:00 h ..................................................................... 173
Appendix 4.2.VSection A of questionnaire given at 12:00, 17:00 and 21 :00 h ................ 176
Appendix 5.1. Accuracy of throwing darts ........................................................................... 177
Appendix 6.1. Gas Analysis Using the Douglas Bags ........................................................... 178
Appendix 6.2. Blood lactate ................................................................................................... 182
Appendix 6.3. BORG scale (Rating of Perceived Exertion) ............................................... 183
XVII
Chapter
I. A Brief Outline of the Thesis
II. An Introduction to Ramadan and
Factors Influencing Normal Food Intake
Liverpool John Moores University
I. A Brief Outline of the Thesis
In part II of this Chapter, an introduction to Ramadan and factors affecting normal food
intake is given. This forms the background to the more general literature review of the effects
of Ramadan in Chapter 2.
In Chapter 2, a review of the literature describing changes in Ramadan due to food and fluid
restriction and changed sleep patterns is given. Any changes in perfonnance and psychology
can arise not only from fluid and food restriction during the daytime but also from sleep loss
(due to rising early and retiring late after a large meal). The literature has rarely distinguished
between these possibilities. Also, many of the studies describe changes during the four weeks
of Ramadan rather than changes during the course of single days. Previous work at Liverpool
John Moores University (LJMU) has investigated within-day changes in two studies using
questionnaires (Waterhouse et al., 2008a, 2008b), and has established that subjective
estimates of physical and mental performance indicate deterioration during the daytime
(accompanied by increased fatigue) and a recovery in the evening when people eat and drink
in the company of friends.
Based on this review, therefore, the two main aims of the present thesis are fonnulated: first,
to build upon previous work at LJMU and investigate in more detail any decrements in
performance, including objective measures, that might develop in Ramadan; second, to
investigate if laboratory-based simulations, using non-Muslim subjects and only one day of
fasting, could simulate the previous changes found in Ramadan.
In Chapter 3, a field study which was performed in Libya of changes in performance and
mood in Ramadan is described. It differs from the previous studies at LJMU in two main
2
ways. First, the subjects, taking a full-time course at a Sports College in Libya, were quite
young (and so living at home with their parents rather than being self-sufficient). Second,
because of their place of study, the students could be tested in a fully equipped sports
laboratory. The results enable a fuller picture of the decrements produced by the demands of
Ramadan to be obtained. Some differences from the previous work are found, and these can
often be attributed to the subjects' not having domestic responsibilities nor having to look
after themselves.
In the first part of Chapter 4, the relative advantages and disadvantages of field vs. laboratory
studies are considered. It is concluded that, although field studies are "real", they have severe
limitations when a variety of measures of performance is to be attempted. In the second part
of this chapter, the first laboratory-based simulation of Ramadan, a pilot study, is described.
This is a "simulation" of Ramadan for two main reasons. First, subjects undertook fasting
between the hours of sunrise and sunset but for one day only. Second, the subjects were non
Muslims and so had no experience of Ramadan. The results show that many of the changes
observed in the field study are also observed in this laboratory-based study. Some of the
implications of these findings are that decrements in subjective and objective measures of
performance during Ramadan can be studied much more simply and upon naIve subjects.
Such positive results opened the way for a more complex study to be performed, and this
study is described in Chapter 5. More variables than were measured in the field study and the
pilot study were considered, and the variables were measured at more time-points than in the
pilot study. The results confirm that objective and subjective measures of performance show
decrements during the daytime when fasting, and they also confirm that physiological
evidence for dehydration is present. The results add substantially to the information obtained
3
from the field study; taken together, and with the previous work (Waterhouse et ai. ,2008a,
2008b), they are the fullest account of changes taking place during the course of a day in
Ramadan.
One factor that was present in the previous field studies was "fatigue", due to reduced sleep
times (subjects rising before sunrise to eat and drink and tending to recuperate from daytime
fasting by eating and drinking substantial amounts after the end of the fast). Such sleep
causes poorer mental and physical performance (Reilly et aI., 1997; Waterhouse et ai., 2001)
independent of food and fluid restriction (Reilly and Waterhouse, 2009). Therefore, the
poorer performance might have reflected effects due to less sleep as well as restricted food
and fluid intake.
In Chapter 6, an intervention study is described in which sleep and daytime activities are
controlled while the amount of time spent fasting is manipulated. This protocol means that
any changes cannot be attributed to changed sleep or daytime activity. The results show
decrements in subjective and objective measures of performance and dehydration, as in the
previous studies. That is, food and fluid restriction, independent of any sleep loss, have a
negative impact upon these variables.
In Chapter 7, the results from the studies are summarized and conclusions drawn with regard
to the negative effects of fasting upon some variables. Further, there is a discussion of the
value to an understanding of some of the effects of Ramadan of protocols involving only a
single day of fasting in laboratory-based studies rather than field studies covering the whole
month of Ramadan. In addition, there is a consideration of the choice of subject for such
studies - whether naIve or experienced with regard to the practice of Ramadan (non-Muslim
4
vs. Muslim subjects) and whether living independently (Waterhouse et ai., 2008a, 2008b) or
at home (Chapter 3).
Recommendations for further studies follow: there is need for more sensitive measures of
some aspects of physical performance (or for a more extensive training in these measures
together with stricter conditions for their performance). There is also need for an
investigation of the possible interactions between the effects of sleep restriction and fasting,
and for more objective measures of sleep quantity and quality.
The thesis concludes with a section describing the implications of the results that have been
found.
5
II. An Introduction to Ramadan and Factors Affecting Normal Food Intake
1.1. The Timing of Ramadan
The Islamic calendar is a lunar calendar based on 12 lunar months in a year, and lasts 354 or
355 (solar) days. It is used to date events in many Muslim countries, and used by Muslims
everywhere to determine when to celebrate Islamic holy days. Ramadan is the ninth month of
the Islamic calendar; it is the month of fasting, in which participating Muslims refrain from
eating or drinking from dawn until sunset.
As Ramadan is dependent on the moon and a year lasting about 354 days, the dates of
Ramadan move forward about ten days each year as judged by the Gregorian calendar (which
is based on the solar year, the time taken for the Earth to move around the sun). One effect of
this movement of Ramadan relative to the solar year is that the hours between sunrise and
sunset vary, particularly when moving from equatorial regions (where the day length varies
comparatively little during the course of a solar year) towards the Poles. In the UK, for
example, the time interval between sunrise and sunset can be as little as about 8 h (at the
winter solstice) and as much as 16 h (at the summer solstice). In the year 2008 (when the
field study described in this thesis took place), Ramadan fell between August 31 st and
September 30th, and the interval between sunrise and sunset was about 13 h.
Ramadan begins with the new (crescent) moon but there are disagreements each year as to
the exact day on which Ramadan starts. This stems from the tradition in some countries to
6
sight the moon with the naked eye whereas, in other countries, astronomical calculations are
used (so overcoming the problem of poor seeing conditions due to cloud, for example). The
crescent moon is typically a day after the astronomical new moon and so different countries
might start Ramadan at times differing by a day. More recently, there has been a tendency to
use astronomical calculations to avoid this confusion.
1.2. The Requirements of Ramadan
During the holy month of Ramadan, Muslims abstain from food and fluid intake between
sunrise and sunset (Zerguini el aI., 2007); however, food and fluid intakes are freely allowed
from sunset to dawn (Roky et aI., 2004). In practice, individuals prepare for the period of
fasting by rising earlier and eating a meal similar to their usual breakfast before sunrise, and
recover after sunset by eating and drinking a wide variety of foods and fluids to replenish
energy and fluid levels (Karaagaoglu and Yucecan, 2000), usually in the company of a group
of friends. That is, fluid and food intakes become exclusively nocturnal (Hakkou et aI.,
1994).
Karaagaoglu and Yucecan (2000) reported on the nutritional habits of 750 adults (320 males
and 430 females) aged from 20-75 years. 95% of the subjects stated that they consumed two
meals per day, the "Sohor" and the "Ichaa". The "Sohor", consumed shortly before sunrise,
consisted mainly of breakfast foods such as cheese, olives, sausage, eggs, jam and/or
marmalade and tea. The "Ichaa", consumed shortly before retiring to bed, consisted of soups,
vegetable foods, rice, salads or fresh vegetable, fruit and yoghurt. At this meal also, about
62% of the subjects drank tea. Special foods such as "pide", a form of flat bread only baked
7
during the month of Ramadan, was also reported to being frequently consumed by the
subjects. That is, not only is the timing of food and fluid intake altered in Ramadan but also
there is a change in some aspects of the Muslim's diet.
Fasting during Ramadan displaces energy intake and hydration to the hours of darkness and
so also disrupts the sleep-wake cycle. Sleep is curtailed and subjects feel more tired in the
daytime and tend to take more naps and rest more at this time (Waterhouse and Reilly, 2007).
As a result of the changes imposed by the demands of Ramadan, it is associated with more
daytime fatigue and less physical and mental activity than on normal days (Waterhouse et a/.,
2008a, 2008b; Yacine et al., 2007).
1.3. Effects of Changed Eating Habits in Ramadan
1.3.1. Normal eating habits
The main role for food intake is to satisfy the biological need of obtaining the nutrients
required for energy growth and repair. However, humans have invested mealtimes with other
purposes including business and social roles - such as working breakfasts, business lunches,
meals with friends, and extensive meals to celebrate a special occasion like a wedding feast.
By contrast, food intake can at least temporarily fall behind biological requirements when
individuals are busy or might even forgo the meal due to lack of time available (Reilly et aI.,
1997). There are also occasions when food and fluid intake are temporarily altered as during
religious fasts. That is, food intake and responses to it are caused by exogenous factors -
including general lifestyle, culture, time pressure and social factors - as well as biological
need (Bogdan et aI., 2001; Waterhouse et aI., 2005).
8
1.3.2. Effects of time of meal upon total daily intake
During a normal nychthemeral lifestyle, daytime activity and nocturnal sleep, food is eaten
almost entirely in the daytime (de Castro, 2004). Changes in mealtimes might arise due to
work schedules, restricted food availability and social influences (Bogdan et al., 2001). In
some circumstances, these changes in food and fluid intake will affect amounts of physical
activity that are undertaken. Many studies have indicated that there is a relationship between
the time of day when food is eaten and the total daily intake; eating early in the day tends to
decrease overall intake, whereas taking in more food later in the day tends to increase the
total daily intake (de Castro, 2004). However, in general, meal size increases over the course
of the day and the amount of time that the individual waits before eating again, the post-meal
interval, decreases (de Castro, 2001).
1.3.3. Factors affecting food intake
Several factors alter what individuals eat and when they do so.
1.3.3.1. Cultural
The distribution of the macronutrients differs between cultures and countries (Bellisle et al.,
1998) and the time when the main meal is eaten are influenced by cultural and socio
economic differences (de Castro, 1997, 1999,2000; Gatenby, 1997; Shepherd, 1989; Wilson,
2000; Winkler et aI., 1999). The timing can also differ between days of work and days of
rest. In Libya, for example, it is normal to have the main meal at lunchtime on Friday, after
prayers; in the UK, by contrast, the main meal is in the evening, except on Sundays when it is
at lunchtime.
9
1.3.3.2. Social factors and time availability
Social factors exert a large influence upon the size of meal that is eaten and when it is eaten
(de Castro, 1997, 1999,2000; Gatenby, 1997; Shepherd, 1989; Wilson, 2002; Winkler et aJ.,
1999). Therefore, meals are larger and are enjoyed more on rest days compared with
working days (Waterhouse et al., 2003, 2005), partly because, during rest days, there is more
time to prepare and eat a large meal and the meal itself can take on a social role with friends
and family (Waterhouse et al., 2005). Conversely, restricted time availability and its social
associations can limit the size of meal. Lack of time availability and social factors also affect
subjective responses to food, such as hunger before a meal, enjoyment of the meal itself, and
satiety afterwards (Marshall and Bell, 2003;Weber et aI., 2004).
These factors influencing food intake are also illustrated by eating habits during shift work
(for example: Krauchi et aJ., 1990; Lennernas et al., 1994, 1995; Nikolova et aI., 1990;
Reinberg et aI., 1979; Tepas, 1990; Walker et aI., 1985; Waterhouse et al., 1992, 2003, 2005)
and after time-zone transitions (for example: Waterhouse et aI., 2003, 2004, 2005). Such
differences in eating habits will also be reflected in the processes of digestion, absorption and
metabolism of food. However, it is known that many of these processes are also affected by
the "body clock".
1.4. The Body Clock and Circadian Rhythms
Accepting that food intake might be affected by "internal" (the body clock) as well as
external (food availability) factors, the role of the body clock in food intake and its
metabolism must be considered.
10
The circadian clock, located in the suprachiasmatic nuclei (SCN) of the hypothalamus,
regulates daily variations in numerous physiological processes such as sleep-wakefulness,
temperature, and hormone release, as well as cognitive performance (Reilly et aI., 1997).
These nuclei are linked neurally to the eyes via the retinohypothalamic tract and they receive
a humoral input from the pineal gland. The pineal gland secretes the hormone melatonin
during the hours of darkness and there are melatonin receptors in the SCN (Khalsa et aI.,
2003). These two pathways provide a means of responding to the presence and absence of
light.
A daily trough in body temperature occurs about 1.5-2 hours before the usual wake time. This
is close to the time of a daily trough in alertness and cognitive performance. Thus the
circadian clock is programming the body for maximal sleepiness in the early morning hours
(about 03:00-05:00 h for a person on a typical sleep-wake schedule) and alertness during the
daytime (Neri et af., 1997). The clock is important also in allowing the future to be predicted,
thus allowing preparations for sleep and waking (Moore-Ede, 1986). It is a common
experience, for example, that the evening is a time of decreasing alertness and increasing
readiness for sleep itself, and many physiological and biochemical changes accompany such
progressions. Human subjects cannot suddenly go to sleep, nor can they suddenly awaken
and work efficiently; the clock, often aided by our chosen lifestyle, enables us to prepare for
these profound changes in neurophysiology (Reilly et af., 1997).
1.4.1. The role of the body c10tk
Human beings are day-orientated, having evolved to work in the daytime and sleep at night.
Our internal body rhythms normally cause regular variations in individual body and mental
11
functions with a period of 24 hours. For instance, our body temperature, heart rate, blood
pressure, breathing rate and adrenaline production normally rise during the day and fall at
night (Reilly et aI., 1997).
The circadian rhythm of core temperature is associated with widespread effects throughout
the body, and it is believed to be one of the main determinants of the difference between the
active "ergotropic" phase when awake and the "trophotropic" phase when asleep. The rhythm
of core temperature is correlated with rhythms of sleep propensity (Dijk et al., 1995),
physical performance (Waterhouse et al., 2005), and mental performance (Waterhouse et al.,
2001) Also, it must, like melatonin (the hormone released in darkness by the pineal gland), be
considered to be an internal Zeitgeber for the organism, synchronizing different circadian
functions and, particularly, peripheral oscillators (Brown et al., 2002). The circadian changes
of body temperature seem to be involved in the regulation of the circadian sleep-wake cycle
(Van Someren et al., 2000). An individual normally falls asleep when core body temperature
is decreasing, and the main sleep period ends on the rising part of the circadian temperature
curve. It is unlikely, however, that the core body temperature (and, thus, the brain
temperature) is causally involved in the modulation of sleep propensity. Skin temperature
may, instead, be a better candidate for providing a signal to sleep-related neurons (Van
Someren et a/., 2000).
These rhythms influence task performance and quality of sleep. Most of the body's basic
functions show maximum activity by day and minimum activity by night. The biological
rhythms affect the behaviour, alertness, reaction times and mental capacity of people to
varying degrees. The risk of car crashes increases when the driver is driving at times when he
12
or she would normally be asleep; there is also an increased crash risk during the mid
afternoon "siesta hours" (Roky et al., 2004).
1.4.2. The role of the body clock in regulating food intake
The role of the body clock in determining food intake can also be assessed directly only by a
"forced de synchronisation" protocol (Kleitman, 1939). In this protocol, subjects are required
to live on an imposed sleep-wake schedule, associated with which is an altered light-dark
cycle, which is beyond the range of entrainment of the body clock. Under these
circumstances, measured rhythms show two components - an exogenous component due to
the imposed "day" (the sleep-wake schedule) and an endogenous, circadian component due
to the "free-running" body clock.
Waterhouse el al. (2004) investigated food intake during such a forced desynchronisation
routine, using an imposed "day" of 28 h. They found that there was only a very weak
endogenous influence on food intake; individuals continued to eat meals of normal size and
to enjoy them normally as measured by the imposed daytime. That is, a large meal was eaten
and enjoyed towards the end of the day (dinner), whatever the circadian time.
Nevertheless, other aspects of the whole process of food intake are affected more by the body
clock. There are many metabolic differences between the day night, including the metabolism
of glucose and fat. Thus, in the daytime and due to food intake and insulin and adrenaline
secretion, there is a tendency to metabolize glucose and to store fat in adipose tissue; by
contrast, at night under the influence of changed levels of insulin, growth hormone and
adrenaline, the body tends to metabolize fat instead (AI-Naimi et aI., 2004). There are also
13
changes in gut activity. Such rhythmic changes in gut function and metabolism have a strong
exogenous component, but there is also some effect due to the body clock (Waterhouse ef a/.,
1990). Therefore, altered food intake at night might be due partly to the effects of a poorly
adjusted body clock (Tepas, 1990).
In summary, under normal circumstances, food intake plays many roles and it is influenced
by many factors. However, in Ramadan, these factors tend to be overridden by the religious
requirement to fast. A summary of the changes produced by fasting in Ramadan will be
considered in the literature review of Chapter 2.
14
Chapter 2
The Demands and Effects of Ramadan:
Review of the Literature
~~.:
~t~ JMU
Liverpool John Moores University
To summarise the position, fasting in Ramadan during the daylight hours results in many
changes (reviewed in Benaji et al., 2006; Leiper et al., 2003; Reilly and Waterhouse, 2007;
Roky et al., 2004). During Ramadan, nocturnal sleep is shorter and its architecture is changed
(Roky et al., 2003); there is also an increase in the number of naps taken during the daytime
(Margolis and Reed, 2004), so reducing daytime somnolence. The change in distribution of
the hours of sleep and waking is believed to be responsible for negative effects upon mood
and the willingness to work (Karaagaoglu and Yucecan, 2000), and decreased abilities to
perform physical and mental activities optimally (Kadri et aI., 2000; Roky et al., 2000). An
increase in road traffic accidents has been reported (Roky et aJ., 2004), though this has not
always been confirmed (Kammash and AI-Shouha, 2006). There are also several metabolic
changes, including a fall in body mass and an increase in the ratio: [high-density lipoprotein
cholesterol]1 [low-density lipoprotein cholesterol] (Qujeq et al., 2002; Roky et al., 2004).
These issues will be discussed in more detail in the following sections of this chapter.
2.1. Effects of Ramadan upon Body Weight, Metabolism and Sleep
Over the course of the four weeks of Ramadan, the altered patterns of food and fluid intake
change daytime body composition and metabolism (Sweileh et al., 1992). In addition, less
sleep (by up to two hours) is taken at night (Roky et al., 2001). This results in decreased
daytime alertness (Roky et aI., 2004) and has detrimental effects on physical and mental
performance. These factors will be discussed in turn.
16
2.1.1. Body weight, fluid intake and water content.
Water is the largest single component of the human body, accounting for about 50-60% of
total body weight. In the short tenn, the maintenance of body water stores is vital and this
will be compromised during the daytime in Ramadan. Water balance depends on the balance
between fluid intake and urine excretion; therefore, lack of water intake during the period of
fasting causes concentration of all fluids within the body. This is compensated for by water
conservation by the kidneys, concentrated urine being produced (Bouby and Fernandes,
2003). Fluid intake is due to thirst but, in Ramadan, such feelings have to be ignored in the
daytime (Leiper and Prastowo, 2000).
Some studies have reported that the substantial dehydration is accompanied by raised serum
concentrations of uric acid and cholesterol (Toda and Morimoto, 2000). By contrast, Leiper
and Prastowo (2000) found that total body content was conserved during Ramadan. The
decrease in water intake in the daytime was compensated at other times of the day;
individuals increased fluid intake during the night after sunset, and rose before sunrise, to
prepare for the daytime restriction in fluid intake (Leiper et ai., 2003; Waterhouse et ai.,
2008a, 2008b).
It has been reported (Leiper et ai., 2003) that the stress of dehydration in the daytime during
Ramadan is not detrimental to the health of fasting Muslims (as assessed from medical
records), and that no ill effects can be attributed to the intennittent negative water balance at
the leVels that may be produced during Ramadan. However, these observations apply to
individuals living nonnally and need not apply to those who are undertaking heavy exercise
during the daytime.
17
Changes in body mass are controversial. Studies report an increase in body mass (Khatib et
aI., 1997; Khatib et aI., 2004; Mafauzy et al., 1990), a decrease (Khaled et al., 2006; Klocker
et al., 1997; Yarahmadi et al., 2003) or no significant change, but sample sizes were small
and activities were not controlled. Most of these authors suggest that a decrease in body
weight is related to a decrease in calorie intake, while an increase is correlated with increased
food intake coupled with a reduction of daily activities.
2.1.2. Food intake and metabolism.
Food intake is essential for obtaining the nutrients for energy and growth. Abstaining from
food intake in Ramadan reduces total energy levels and gives rise to hunger. Normally, the
type and size of a meal is influenced by social factors and the environment in which the food
is eaten as well as hunger (De Castro, 1997; 2000; Marshall and Bell, 2003; Meiselman et al.,
2003; Rappoport et aI., 2001; Stroebele and De Castro, 2004; Weber et aI., 2004), but these
factors change in Ramadan where the main considerations will be preparations for the period
of fasting and recovery from it.
Fasting during the daylight hours results in many changes in metabolism (Benaji et al., 2006;
Leiper et al., 2003; Roky et al., 2004). Although total energy intake is decreased during
Ramadan, so is energy expenditure, this being associated with a lower activity profile in the
daytime. Even so, there is a tendency for weight loss and negative energy balance. This
decrease in daily calorie intake has been seen as one of the advantages of fasting in Ramadan
(Bouguerra et aI., 2003; Khaled et aI., 2006; Sari et al., 2004), in addition to which, it is
reported that levels of free cholesterol fall in Ramadan (Scheen, 1999).
18
Food intake leads to increased gastrointestinal activity and so patterns of gastrointestinal
function are normally in phase with a diurnal eating pattern, with more gut activity in the
daytime (Waterhouse et aI., 1999).
Figure 2.1. Changes from normal days in hunger, top, and amount of indigestion, bottom, in a group of 12 subjects who underwent a 25-h constant routine. Mean + SE shown. (From Waterhouse et aI., 1999a).
19
Accordingly, the altered pattern of food intake in Ramadan is predicted to change the timing
of gut function in a similar way, but no detailed studies of this have been performed.
However, this prediction is based on the assumption that gut function follows food intake
whatever the time of day, and there is some evidence that this need not be the case. Figure 2.1
shows the mean levels of hunger and indigestion in a group of 12 subjects during the course
of a constant routine. In this routine, subjects were kept awake in a constant environment
(temperature, humidity and lighting) for 25 hours, starting after a full night's sleep that ended
at 08:00 h. At the end of each hour awake, the subjects were given a small sandwich and
drink of fruit juice. Immediately before these snacks, they were asked to rate their hunger on
a scale from -5 (not at all hungry), through 0 (as hungry as normal) to +5 (very hungry).
They were also asked to rate any feelings of indigestion or feeling overfull from 0 (none) to
+5 (marked). It is clear that during their normal waking hours (the first 16 h of the constant
routine) their hunger was normal and they suffered little from indigestion or feeling overfull.
However, during the night (hours 17+), their hunger fell and their sense of indigestion and
feeling over-full increased. That is, it seems that the ability of the gut to absorb ingested food
might be compromised at night.
Since the normal pattern of eating and drinking is altered in Ramadan, many changes in
metabolism result, mainly those associated with the metabolism of glucose and fat. Thus, in
the daytime under normal (non-fasting) conditions, food intake and the increase in insulin
secretion produced by it promote the uptake of glucose by the cells of the body and its
metabolism, and also to increased fat storage in adipose tissue; by contrast during nocturnal
fasting the body tends to metabolize fat instead (AI-Naimi et ai., 2004). This pattern will be
substantially altered during Ramadan, and increased metabolism of fat stores in the daytime
20
and increased metabolism of glucose during the night after the evening meal is predicted.
This change will require the secretion of hormones associated with metabolism (insulin,
growth hormone, glucagons, cortisol, for example) to change also. Details of these changes
remain to be investigated. However, it is known that the different hormones are influenced to
different extents by the body clock, and so it cannot be assumed that all will change their
pattern of secretion to the same extent (Waterhouse et al., 1999a).
2.1.3. Sleep
Studies have demonstrated that the average adult human requires 8-8.25 h of sleep for
optimal performance and alertness (Dinges, 1995), but there is a range of individual sleep
requirements around this amount (about 6-10 h). Episodes of acute sleep loss can build into a
cumulative sleep debt; it is important to provide adequate opportunity to minimize such a
debt, and to provide adequate recovery sleep if this loss does occur (Neri et al., 1997).
Because, during Ramadan, all meals are consumed at night, they tend to affect the amount of
sleep fasting Muslims are able to obtain. Many studies indicate that nocturnal sleep is
reduced in length. Hakkou et al. (1994) suggested that sleep was reduced by approximately 3
h due to the time taken to eat meals before sunrise and after sunset. Roky et al. (2003, 2004)
also showed that the percentage of people who went to sleep after midnight increased during
Ramadan; sleep duration was less than 6 h in 68% of 150 workers during Ramadan but in
only 37% before Ramadan. Sleep loss can degrade many aspects of human performance,
including memory, vigilance, decision-making, mood, and reaction time (Waterhouse et ai.,
2001). Bahammam (2003, 2004) investigated the effect of Ramadan on sleep architecture,
daytime sleepiness and sleep patterns in 8 healthy Muslims. Compared to baseline (non
fasting days), bedtime was delayed in the first and third weeks of Ramadan with delays of 1 h
21
18 min and 1 h 36 min, respectively. These delays were coupled with a constant wake up
time, which caused a significant reduction in nocturnal sleep time. This reduction in sleep
causes daytime fatigue but there is also an increase in the amount of sleep taken during the
daytime (Bahammam, 2003; Margolis and Reed, 2004; Roky et at., 2003), so reducing the
total sleep loss.
During Ramadan, many people alter their sleeping habits considerably, staying awake most
of the night and sleeping much of the daytime (Wilson et al., 2009). This has the advantage
that food and fluid can be taken in during the waking period but the subjects are then similar
to night workers and this produces other problems due to lack of adjustment of the body
clock (Waterhouse et at., 1992).
Changes in the pattern of food intake in Ramadan are the main cause of reduced nocturnal
sleep at this time, but there are further interactions between food intake and sleep loss. First,
going to bed with a full stomach might cause discomfort and hinder sleep. In addition,
drinking copious amounts of fluid and caffeine-containing drinks could affect the quantity
and quality of the sleep (Roky et at., 2001). Second, sleep deprivation seems not to increase
appetite (it might even make individuals lose interest in food) but rather leads to a preference
for foods containing more energy (Spiegel et aI., 2004).
2.2. Ramadan and Physical and Mental Performance, Mood and Social Activity
Mental and physical performance, mood and social activity are affected by many factors
including sleep loss and fluid and nutritional status (Reilly and Waterhouse, 2007). As a
result, it is to be expected that these performance and cognitive variables will change during
Ramadan.
22
2.2.1. Mental performance and fatigue
Many aspects of mental performance normally improve in the hours after waking, reach a
peak around the middle of the day and fall in the evening. These profiles are caused by an
interaction between core temperature and time awake (Minors and Waterhouse, 1981 ;
Waterhouse et aI., 2001). Core temperature rises in the morning after awakening and peaks in
the later afternoon before falling in the evening. In principle, mental performance follows this
rhythm, cognitive processes being improved by a rise of temperature in the physiological
range (Reilly et al., 1997). In addition, however, the factor time awake tends to cause a
decrement in performance. This factor is minimal after awakening and increases
progressively while the subject remains awake. The effects of increasing time awake depend
upon the type of task. For simple measures of mental performance (simple reaction time, for
example), the time-awake effect is small and so the rhythms of core temperature and
performance are similar. By contrast, for mood and mental tasks which have a larger
cognitive component (decision-making, for example), the time-awake effect is greater. As a
result of this, the time of peak performance at such measures is earlier in the daytime, around
noon (Folkard, 1990).
Optimal sleep, both in quantity and quality, is necessary for maximal performance and
alertness. Reduced (of as little as 2 h) or degraded sleep can significantly decrease or impair
alertness and mental performance, including memory, vigilance, decision-making, mood and
reaction time tasks (Waterhouse et ai., 2001).
The change in distribution of the hours of sleep and waking in Ramadan is believed to be
responsible for negative effects upon mood and the Willingness to work (Karaagaoglu and
Yucecan, 2000) and decreased abilities to perform mental activities optimally (Kadri el al.,
2000; Roky et aI., 2000). Lack of concentration, tiredness, irritability, sleepiness and other
23
undesirable symptoms during the daytime, which may have negative effects on the working
and school life of individuals, have been described, as have a decreases in alertness and
cognitive ability and an increase in irritability (Afifi, 1997; Kadri et al., 2000; Karaagaoglu
and Yucecan, 2000; Taoudi et aI., 1999). An increase in road traffic accidents during
Ramadan has also been reported (Bener et al., 1992). Cognitive function has also been shown
to deteriorate (Roky et al., 2000). In addition, a frequently cited problem of Ramadan fasting
is an increased incidence of headaches; however, the effects of restrictions on smoking
tobacco ingesting caffeine and energy and fluid intake must also contribute to this general
negative feeling. It has been noted that most of these changes do not show a progressive
deterioration during the four weeks of Ramadan (see, for example, Kadri et al., 2000; Leiper
et al., 2003; Roky et al., 2004), suggesting that Muslims rapidly adapt to the demands of
Ramadan.
It is not only decreased sleep that is responsible for these changes; Roky et al. (2004)
concluded that daytime subjective alertness during Ramadan, evaluated by a visual analogue
scale (in which subjects scored how alert they felt on a scale), decreased at 09:00 hand 16:00
h and showed an increase at 23 :00 h. They concluded that reduced energy intake was
responsible as well as sleep loss. The role of decreased food intake is supported by the
observations of improved mood in the evening after fasting has ended. An additional factor
contributing to this improvement is likely to be the increase in social activity that also occurs
at this time.
It is generally accepted that there is also a strong relationship between eating, alertness and
mood (De Castro, 1997; 2000; Marshall and Bell, 2003; Meiselman et al., 2003; Rappoport et
aI., 2001; Stroebele and De Castro, 2004; Weber et al., 2004). Mental performance is affected
24
by a wide variety of factors, including energy levels or tiredness, tension, anxiety, depression,
relaxation, stimulation/excitement and motivation. Published research increasingly supports a
role for food in maintaining mental performance and mood - particularly a role for
carbohydrates (Bellisle, 2002). Food and fluid restriction, therefore, might contribute to
negative effects on mood, mental performance and irritability observed during Ramadan.
Part of this mood change is believed to be caused also by alterations in normal circadian
rhythms. These alterations are due to individuals becoming more active through the evening
and night (Taoudi Benchekroun et al., 1999) and to their changed sleep patterns (Bogdan et
aI., 2001; Husain et al., 1987; Roky et al., 2001). In addition, the effects of restrictions on
smoking tobacco and ingesting caffeine must also contribute to this general negative feeling.
Proper hydration is important for optimal cognitive functioning, as it plays a vital role in
neural conductivity (Kleiner, 1999), as well as for efficient digestion, elimination of toxins,
thermoregulation,joint lubrication and energy production (Felesky-Hunt, 2001). In support of
this role of hydration, Sharma et al. (1986) found that dehydration of 2-3% of body mass
resulted in poorer performance on tasks requiring concentration and speed of psychomotor
processing. Similar results were also reported by Cian et al. (2000), subjects showing
decrements in performance during test of short-term memory, attention and psychomotor
speed tests when dehydration reached levels of2% or more of body mass.
2.2.2. Physical performance
In contrast to mental performance, muscular performance in general is little affected by sleep
loss (Reilly and Waterhouse, 2009). However, to the extent that physical performance
25
includes, in addition to muscle contraction, elements of mood, perceived exertion, sensori
motor co-ordination, cognitive performance and motivation, it will also be negatively
affected by sleep loss. The effects of fluid restriction on performance have been much
researched over recent years. A water deficit of only a few percent will impair physical
performance (where integrated activity between muscle groups is required) but not muscular
strength (Barr, 1999; Maughan, 2003); a slightly larger loss will bring about symptoms of
tiredness, headache and general malaise (Maughan, 2003).
Restricted food intake also has negative effects, and the general view is that altered eating
and drinking schedules negatively impact upon the duration and intensity of physical activity
that can be performed (Benaji et al. ,2006; Leiper et al. ,2003; Reilly and Waterhouse, 2007;
Roky et al., 2004). In Ramadan, training or a competitive event scheduled at 14:00 h could
well be more than 8 h after the player's last meal and several hours before their next meal,
which is outside the window for optimal glycogen replenishment (Reilly and Waterhouse,
2007). Oliver et al. (2006) investigated 48h of food, fluid or food and fluid restriction on 30-
min running performance. Compared with the control group (who received normal levels of
fluid and food during the 48h), the restricted group completed 15% less distance.
Comparatively few studies have directly examined the effects of fasting during Ramadan on
physical performance and the results conflict. Meckel et al. (2008) investigated the effect of
the Ramadan fast on various physical performance measures in adolescent soccer players.
They found a significant reduction in jump height performance, the time taken to run 3,000 m
and speed endurance and attributed the changes to the lack of daytime fluid ingestion.
Decreases in maximal voluntary contractions (MVC) have been measured (Bigard et al.,
1998); maximum isometric strength fell by 10-12%, and muscular endurance at 35% and
26
55% V02max caused MVC decreases of28% and 22%, respectively. Levels of insulin, blood
glucose, low energy levels and mood are potential reasons for these decreases in performance
(Reilly & Waterhouse, 2007). Other studies have shown there to be no decrease in
performance in Ramadan. Zerguini et al. (2008) summarised the 2006 F-MARC Ramadan
Study in which various endurance and anaerobic performance variables were measured in
athletes undergoing training in Ramadan. It was found that performance was not negatively
influenced by the restriction of food intake during testing. Similarly, Kirkendall et al. (2008)
tested subjects for speed, power, agility, endurance and soccer specific skills and found no
performance decrements in Ramadan.
Such a divergence of findings has been found also in investigations into the effects of fasting
on strength and maximal power output. Karli et af. (2007) investigated short-term high
intensity exercise using the Wingate anaerobic test and observed that there was no influence
of Ramadan fasting on anaerobic capacity. Conversely, Souissi et al. (2007) demonstrated
that Ramadan fasting was associated with reduced anaerobic power. It is clear that more data
are required to resolve these differences.
It is of interest to note that restrictions of energy and fluid intakes frequently occur
intentionally when athletes are required to achieve weight standards (Horswill et al., 1990)
or, in wrestling, to adhere to weight classifications (McMurray et al., 1991). Many Judo
athletes compete at a weight class 5-10% below their natural weight, achieved through
restricted calorie intake before competition (Degoutte et al., 2004). However a later study
(Degoutte et al., 2005) concluded that muscle strength declined, thereby decreasing
performance. Also, Hall and Lane (2001) reported that boxers restrict fluid and energy intake
in the week leading up to a fight in order to lose mass and compete in a lower weight class.
27
The evidence, though ambiguous, is sufficient to indicate that physical performance might be
compromised in Ramadan, and there is a need to explore strategies to optimise physical
performance during Ramadan (Yacine et al., 2007).
2.3. Clinical Implications of Ramadan
The changed pattern of food intake in Ramadan raises the possibility of medical problems in
susceptible individuals, particularly in patients with, for example, hypertension,
hypercholesterolemia, hyperglycaemia and heart, liver or kidney disease (AI-Naimi et al.,
2004). It has also been argued that eating certain types of food at inappropriate times may be
a factor in gastrointestinal complaints and may predispose individuals to becoming
overweight (Iraki et al., 1997).
During the fast, the individual must abstain from oral medication (Azizi and Siahkolah,
1998), and this might lead to problems in diabetic individuals (8enaji et al., 2006). In type 2
diabetes, patients change their treatment regimen in accord with the altered pattern of food
intake in order to reduce the risk of hypo glycaemia (Fereidoun and Siahkolah, 1998). Few
studies have assessed the effects of changed food intake in diabetics, and those that have been
performed deliver conflicting results. Even so, it is generally stated that fasting in Ramadan
does not pose a risk to diabetics whose blood sugar and general metabolism are under control,
just as there are no problems for those who are at increased cardiovascular risk (Khaled et aI.,
2006; Sulimani et al., 1991).
2.4. Changes During the Course of the Day
This brief review of the scientific literature relating to some of the effects of fasting during
Ramadan indicates that the effects are widespread. However, most of the literature describes
28
only the changes in Ramadan in comparison with normal, non-fasting days, comparing results
obtained at the same time of day; most studies do not consider what happens during the
course of the passage of the day in Ramadan. Information on this issue requires within-day
changes to be investigated.
Very little literature exists on this aspect of the problem. However, there are two studies that
have been performed by the group in Liverpool. These studies have considered in much more
detail how individuals respond to the demands of Ramadan during the course of single days
(Waterhouse et al., 2008a, 2008b). In both these studies, individuals were compared before,
in the first and fourth weeks of Ramadan and in the week after Ramadan. Assessments of
their sUbjective assessments of fatigue and activities (actually performed and the amount of
these activities wished for by those fasting), together with the reasons for sleeping, eating or
drinking or not doing so were performed both in England and, as a comparison, in Libya. The
general findings were that activities in Ramadan were decreased during the daytimes and
increased in the evening after the fast had ended. This is illustrated by Figure 2.2. Moreover,
the reasons for sleeping/eating/drinking or not sleeping/eating/drinking differered between
fasting and non-fasting days; during Ramadan, subjects' decisions were influenced less by
appetite and more by fatigue (due to sleep loss) and the needs to prepare for, and recover
from, fasting. Such differences were very similar in both countries (incidentally validating the
concept of performing studies on Ramadan in a non-Muslim country).
29
Figure 2.2. Mean (tSE) profiles of physical activity scores during Control days and Ramadan. (From Waterhouse et aI., 2008b)
The value of this work was in determinining how fasting during Ramadan influenced
physical and mental activities and social contact at particular times of the day. It indicated
that individuals tried to "spare" themselves in the daytime and yet "recover" in the evening
while eating and drinking with friends. However, the limitation of such studies is that
physiological changes and changes in objective measures of physical performance were not
investigated. In the first new study (Chapter 3), some of these limitations will be addressed in
a field study performed in Libya.
30
2.5. Aims and Objectives of the Experiments to be performed
In summary, previous work by the group (Waterhouse et al., 2008a, 2008b) indicates that
there are marked changes during Ramadan in individuals' subjective assessments of types of
activity (physical, mental and social) performed in the daytime, before sunrise and after
sunset. Also, there are changed intakes of food and fluid before sunrise (in preparation for the
fasting period) and after sunset (to recuperate from the fasting period), as well as altered sleep
patterns and daytime fatigue. These results indicate that the questionnaire developed by us
can be used in the field to obtain useful information about these changes, and this tool will
continue to be used, but with slight modifications as required, in the experiments to be
performed. However, objective measures of activity are lacking, and more details of changes
in sleep patterns and the quantity and quality of sleep are required.
Such studies can take two general forms, field studies and laboratory-based studies, and both
of these approaches will be used in four new studies that are described in Chapters 3-6.
31
Chapter 3
Effects of Ramadan upon Physical
Activity: a Field Study
~~.:
~t~ JMU
Liverpool John Moores University
This study has been published in Biological Rhythms Research:
Waterhouse, J., Alabed, H., Edwards, B. and Reilly, T. (2009). Changes in sleep, mood and
subjective and objective responses to performance during the daytime in Ramadan.
Biological Rhythm Research; 40: 367-383.
The following account is a slightly modified version of this publication.
33
3.1. Introduction
Devout Muslims abstain from food and fluid intake between sunrise and sunset during the
month of Ramadan. Such a change produces many effects upon an individual's physiology,
biochemistry and behaviour (reviewed in Chapter 2). It has been shown that sleep is shorter at
night during Ramadan (Roky ef aI., 2003), and increased amounts of sleep are taken during
the daytime to reduce sleepiness (Margolis and Reed, 2004). Mood and the willingness to
work decrease (Karaagaoglu and Yucecan, 2000), as do abilities to perform physical and
mental activities optimally (Kadri et ai., 2000; Roky et ai., 2000). Increased frequencies in
road traffic accidents have sometimes been reported (Roky et ai., 2004), and there are several
metabolic changes (Roky et al., 2004; Qujeq et aI., 2002). Many of these changes - including
those to the circadian rhythms of core temperature (Roky et aI., 2000) and several hormones
(Bogdan et al., 2001) - have been attributed to the altered distribution of the hours of
sleeping and waking.
Most of these studies have concentrated on changes taking place during the course of the four
weeks of Ramadan rather than the course of individual days (Reilly and Waterhouse, 2007).
However, it is known that individuals tend to prepare for the period of fasting during
Ramadan by rising earlier and eating a meal before sunrise; also, after sunset, a wide variety
of food and fluids is taken in as individuals replenish energy and fluid levels and then retire
later than normal (Karaagaoglu and Yucecan, 2000). These changes to individuals' feeding
habits as well as their sleep-wake cycle would be predicted to affect their physiology and
metabolism.
34
Previous work by our group on changes during Ramadan (Waterhouse et al., 2008a, 2008b)
investigated individuals' subjective feelings and responses to food and fluid during the course
of individual days. Less physical, mental and social activities were performed in the daytime,
but there were significant increases after sunset (see Figure 2.2). Similarly, daytime fasting
was compensated for by increased fluid and food intakes in the hours before sunrise and, in
particular, after sunset. In addition, sleep at night was altered in Ramadan, daytime sleepiness
increased and more naps were taken in the daytime, the reason often cited for this being to
catch up on lost sleep.
The limitation of these studies is that physiological changes and changes in objective
measures of physical performance were not investigated. The present study has repeated the
investigations of subjective estimates of daytime activities, sleep and fatigue that were made
in these two studies but it has added measures of hydration status, grip strength and responses
to a set bout of mild exercise. Such measurements can be difficult to perform accurately in
the field but it was possible for the subjects to visit a fully-equipped sports laboratory for the
main test sessions and to perform the other test sessions in the comfort of their own home.
3.2. Methods
3.2.1. Subjects and familiarisation
The experimental testing was performed at the Alahli Football Club (Tripoli, Libya), an
academy for training in Sports Sciences. It took place in the weeks before, during and after
Ramadan, 2008. (Ramadan in 2008 was from August 31 5t to September 30th). Subjects were
recruited by advertisement in the University and by word-of-mouth. The aims and a general
35
outline of the protocol were explained to them, and any questions were answered. The study
was approved by the Research Ethics Committee of Liverpool John Moores University.
Potential subjects who showed an interest in the project were then required to take part in a
familiarisation day at the Academy. During this occasion, anthropometric data were
collected, the subjects were asked which their dominant hand was, the questionnaires that
would be answered and subjective information that would be required were explained, and
subjects practised on the cycle ergometer, adjusting the saddle height, and so on.
Twenty subjects agreed to participate and signed informed consent forms in the presence of a
third, disinterested party. None was a smoker or taking chronic medication. All were male
and aged 18; their mean (SD) height was 1.74 (0.06) m and body mass 66.4 (6.2) kg.
During the experiment itself, the subjects were tested during four separate days. For the 48 h
before each of these days, subjects were required to follow their normal times of sleep and
waking, and not to undergo any period of severe or extended exercise. The four experimental
days were: once in the week before Ramadan, twice during Ramadan (once in the first week
and once in the last week), and then a final time during the week after Ramadan (after Eid).
3.2.2. Protocol and measurements
On each experimental day, subjects were asked to answer a questionnaire at four times (09:00
h, 12:00 h, 17:00 h and 21:00 h). The questionnaire is shown in Appendices 3.2 and 3.3;
translations are to be found in Appendices 4.1. and 4.2. Subjects also gave urine sample at
36
09:00 h, 12:00 hand 17:00 h. At 12:00 hand 17:00 h, the subjects undertook these tasks in
the laboratory, whereas they undertook them at home at 09:00 h and 21:00 h. If subjects
wished, they could return to bed after answering the questionnaire and giving a urine sample
at 09:00 h.
On the occasions when subjects were tested in the laboratory, the protocol was as follows.
(1). Subjects rested quietly for 30 min, during which time the questionnaire was answered
and resting heart rate (HR) was measured. (2). Grip strength was measured and subjects
undertook the cycling exercise. (3). Immediately after the exercise (within 1 minute), HR was
measured again and a sample of blood was taken by pin-prick.
3.2.2.1. Questionnaires
Appendices 3.2 and 4.1 (based on Waterhouse et al., 2008a) shows the questionnaire for
09:00 h, which required information from the subjects about the previous night's sleep
(section A), their fluid intake (section B), food intake (section C) and activities (section D)
before sunrise. The questionnaires at 12:00 h, 17:00 hand 21:00 h asked the same
information but the subjects were instructed that their answers should apply to the interval
since answering the previous questionnaire. That is, the questionnaires at 12:00 hand 17:00 h
included periods of fasting (in Ramadan) and that at 21 :00 h, information about activities
after sunset. For these last three times, section A was modified (Appendices 3.3 and 4.2) and
questions about daytime naps rather than nocturnal sleep were asked. For many of the
questions, subjects were required to state not only if they hadlhad not performed a particular
action (taken a nap, for example) but also their reasons for this choice.
37
Interpretation of the exact meanmg of any question was left to subjects to decide for
themselves, although it was explained that the interpretation should be consistent throughout
the study. Strict anonymity was guaranteed with regard to the answers given. Subjects were
asked not to refer back to previous answers and the results from all questionnaires were
collected (by HA) at the end of the study.
"Fluid scores" and "food scores" were calculated for each subject and time interval as
previously devised by Waterhouse et al. (2008a, 2008b). These scores ranged from 0-4 and
were semi-quantitative estimates of total fluid or food intake during this interval. They were
calculated as follows. For the total fluid intake score: "0" represented no intake; "1" indicated
a "sip"; "2", less than 1 glass/cupful; "3", 1 glass/cupful; and "4", more than 1 glass/cupful. .
For the food intake score: "0" represented no intake; "1" indicated a "snack"; "2", a "small
meal"; "3", a medium-sized meal; and "4", a large meal.
The two control weeks (before and after Ramadan) did not show any significant differences
(paired t-test and Wilcoxon tests), and so they were pooled for each subject ("Controls"). The
results from the two weeks of Ramadan also showed no significant differences and were
pooled ("Ramadan").
For many of the variables (whether or not a sleep was taken, whether or not a drink was
taken, and the reasons for making such choices, for example), the "fraction of possible
occasions" was calculated for each subject (see Waterhouse et aI., 2008a, 2008b). "Fraction
of possible occasions" was calculated for each subject and time interval as follows:-
38
Suppose that a subject had slept in the interval 12:00-17:00 h on one of the two days of
investigation during Ramadan. Then the fraction of possible occasions when a sleep was
taken was 0.50. Further, when the fraction of possible occasions that a particular reason for
sleeping was calculated, the frequency of occurrence of this reason was expressed as a
fraction of the single occasion (as a sleep was taken during this interval on only one day), that
is Oil (this reason not given) or 111 (this reason given). Additionally in this example, when
the fraction of possible occasions that a particular reason for not sleeping was calculated, the
frequency of occurrence of this reason was expressed as a fraction of the occasion (the single
day when a sleep had not been taken in this interval). This approach could not be used if an
individual did not perform an action during a particular time interval on either of the 2 days
(never slept between 12:00-17:00 h, for example); in such cases, it would be meaningless to
assess the reasons for sleeping, although it would be possible to use the results from both
days to assess the reasons for not sleeping.
3.2.2.2. Physiological measures
The choice of measures of physical activity, as well as the exact times of testing, was
restricted by the fact that the participants were all students undertaking a full schedule of
studies.
Heart rate was monitored at 12:00 hand 17:00 h, before and immediately after the bouts of
exercise. A heart rate monitor (Polar, Kempele, Finland) was strapped to the chest and a data
logger attached to the subject's wrist. A resting HR was measured over a I-min period at the
end of the 20 min, after the subjects had answered the questionnaire (Appendix 3.2, 3.3) and
before they gave the urine sample and measured grip strength. Heart rate was also measured a
second time in the 30 s immediately after finishing the bout of exercise.
39
Urine samples were given three times per day (at 09:00 h, 12:00 hand 17:00 h). An aliquot
(50 ml) was stored at 10°C until later analysis for osmolality (Osmocheck pocket pal OSMO,
Vitech Scientific Ltd, Japan), this being used as a measure of general dehydration.
Grip strength was measured at 12:00 hand 17:00 h (Handgrip Dynamometer TRK5106.
Jump MD, Tarek Scientific Instrument Score, Japan). Three measurements were taken from
the dominant and non-dominant hand, and the highest of each set of three values was used for
subsequent analysis. (Edwards et ai., 2005).
The bout of exercise consisted of cycling for 15 minutes on a braked cycle ergometer
(Monark Ergo medic 828E Test Cycle, Electronic Company, Sweden) at a constant load of
120 watts. The rate of turning the pedals, the cadence (defining a single turn of the pedals as a
cadence of 2), was left to individual choice (the higher the cadence, the lower the force that
had to be exerted on the pedals). After the exercise, an estimate of perceived exertion was
made on the Borg scale (Borg, 1998).
At the end of the bout of exercise, blood lactate was analysed using a Lactate Pro Test Meter
(Model LT7010, Arfray Inc, Kyoto Japan). This apparatus required a drop of blood to be
taken from the finger tip by pin-prick, and then it recorded immediately the concentration of
lactate in the sample.
40
3.2.3. Statistics
Comparisons between control days and Ramadan of nocturnal sleep times were made by
paired t-tests. Wilcoxon's z was calculated for comparisons between the non-parametric
variables: sleep quality, frequencies of taking different types of drink, and fractions of
possible occasions given for reasons when not sleeping, drinking or eating.
Analysis of variance with repeated measures was used for parametric measures. The main
factors were Day (2 levels, Controls vs. Ramadan) and Time of Day (up to 4 levels, the 4
intervals, tl-t4, namely: until 09:00 h, 09:00-12:00 h, 12:00-17:00 h, and after sunset). The
additional factor Hand (dominant vs. non-dominant) was used for grip strength. Greenhouse
Geiser corrections were used, and significant differences within the main factors were
assessed using Bonferroni corrections. The SPSS package, version 14, was used. Significance
was set as P<0.05, though occasions where 0.05<P<0.10 have been reported as "marginally
significant". Exact P values have been given; results given as "0.000" in the statistics output
have been reported as "<0.0005".
3.3. Results
3.3.1. Results from questionnaires
3.3.1.1. Nocturnal sleep
Estimates of nocturnal sleep times indicated that subjects went to bed and rose later in
Ramadan. Mean (±SE) times of retiring on Control days were 23:25 h (13 min) and, in
Ramadan, 02:16 h (±20 min); t19 = 8.8, P<0.0005 (paired t-test). Rising times were 09:30 h
C±11 min) and 10:15 h (±7 min) for controls and Ramadan, respectively (tI9= 3.9, P = 0.001).
41
Total time spent in bed fell from 10 h 05 min (±12 min) on control days to 7 h 59 min (±17
min) in Ramadan (t\9 = 7.2, P<0.0005).
Subjective estimates of sleep indicated that subjects went to sleep later in Ramadan (z = 2.09,
p = 0.036). Wake times were later also but the difference was not significant statistically (z =
0.32, P = 0.75). The ease of getting to sleep was felt to be greater in Ramadan (z = 2.54, P =
0.011) even though sleep was not felt to be significantly more refreshing (z = 0.27, P = 0.79).
Alertness 30 min after waking was lower in Ramadan, but not significantly so (z = 1.62, P =
0.11). Food and fluid intakes just before retiring tended to increase in Ramadan (z = 1.88, P =
0.061) and subjects felt that intake of food at this time was more valuable in promoting sleep
than on control days (z = 2.01, P = 0.044).
3.3.1.2. Diurnal naps
During the daytime, naps were taken too infrequently (a total of 3 episodes) to be analysed
statistically. However, the reasons for not sleeping could be analysed (Figure 3.1). In the
daytime (09;00 h - 17;00 h), the reasons "Not Tired" and "Never do" were given less
frequently in Ramadan than on the control days (z = 2.65, P = 0.008 and z = 2.54, P= 0.011
respectively) whereas the reason "Too busy" was given most commonly, particularly in
Ramadan (z = 2.88, P = 0.004). In the evenings (17:00 h - 21:00 h), the reasons "Not tired"
and "Never do" were cited most frequently, but not with significantly different frequencies on
control days and during Ramadan. However, the frequency of citing "Too busy" was
marginally significantly greater in Ramadan (z = 1.93, P = 0.053), even though it was still
cited on only about 20% of possible occasions.
42
3.3.1.3. Fluid and food intake
Since fluid and food intake were not allowed between sunrise and sunset in Ramadan,
comparisons at 12:00 hand 17:00 h between intakes on control days and in Ramadan would
have been meaningless. By contrast, comparisons at 09:00 hand 21 :00 h would have been
possible and would have indicated preparations for, and recovery from, the period of fasting.
However, the responses at 09:00 h indicated that the subjects had included only intakes after
rising but before sunrise. Therefore, investigations of preparations for fasting could not be
performed. However, it was possible to compare intakes at 21 :00 h, when eating and drinking
behaviour to recuperate from fasting were taking place. All subjects drank in the evening,
with mean (SE) fluid scores of 3.85 (0.05) and 3.73 (0.09) on controls days and during
Ramadan, respectively. These scores reached towards the maximum possible of 4.0,
indicating more than one glass or cup of fluid was drunk. Figure 3.2, top, shows that water,
fruit juice and fizzy drinks were consumed most frequently, and coffee or tea was rarely
drunk. In Ramadan, the frequency of drinking water increased significantly (z = 2.14, P =
0.032) and of drinking fizzy drinks decreased significantly (z = 2.81, P = 0.005). There was a
rise in drinking milk in Ramadan but it did not achieve conventional levels of significance
(z=1.56; P=0.12). The main reasons for drinking on control days (Figure 3.2, bottom) were
thirst and being sociable; thirst became a more important reason during Ramadan (z = 2.89, P
= 0.004), at the expense of being sociable (z = 3.42, P = 0.001). All subjects ate in the
43
-Controls CRamadan
0.6
0.4
0.2
0.0
Not Tired Never do Too busy Prohibited
Evening
1.0 -Controls CRamadan ~ -,.Q 0.8 .-~ ~ II.) Q = 0.6 ~ Q ~ .-Q II.) 0.4 = = CJ Q CJ
0.2 ~O CJ = 0.0 a.. ~
Not Tired Never do Too busy Prohibited
Daytime
Figure 3.1 . Reasons given for not napping in the evening (top) and in the daytime (bottom). For explanation of "Fraction of Possible Occasions", see text.
evening, with mean (SE) food scores of 3.58 (0.13) and 3.08 (0.13) on controls days and
during Ramadan, respectively. These scores indicated that a medium-to-Iarge meal was the
norm. Figure 3.3 shows that hunger and being sociable were both cited quite frequently on
control days. However, being sociable decreased significantly during Ramadan (z = 2.84, P =
0.005) and recovery from fasting increased significantly and became cited more frequently
that being sociable (z = 2.07, P = 0.038).
44
~ -Controls CRamadan -..c ...
~ 0.6 ~ ~ Q = ~ Q 0.4 Cot. ...
Q ;
= c.J 0.2 Q c.J
.,c 0 c.J
0.0 ~ a.. ~ Water Tea/coffee Juice Fizzy Milk
Type of Drink
~ -Controls CRamadan - 1.0 ..c ... r:IJ ~ r:IJ 0.8 Q = ~ 0 0.6 Cot. ... Q r:IJ = = ~ 0.4 o ~ ~O
0.2 ~ ~ a..
0.0 ~
Thirsty Sociable Health
Reason for Drinking
Figure 3.2. Top, type of drink taken in the evening on control days and during Ramadan. Bottom, reasons given for drinking. For explanation of "Fraction of Possible Occasions", see text.
45
-Controls CRamadan
0.6
0.4
0.2
0.0
Hungry Sociable Fasting Health
Reason for Eating
Figure 3.3. Reasons for eating in the evening on control days and during Ramadan. For explanation of "Fraction of Possible Occasions", see text.
3.3.1.4. SUbjective estimates of activities and sleepiness
Figure 3.4 shows the mean physical activity (top), social activity (middle) and sleepiness
(bottom) scores at the four times of testing on control and Ramadan days. Physical activity
was least before sunrise (tl), and activity during the daytime (t2-t3) was greater than after
sunset (t4). Statistically (Table 3.1), there was no significant effect of Day but a highly
significant effect of Time and interaction between Time x Day. The significant interaction
reflects the tendencies for lower activities in Ramadan during the daytime and higher
activities before and after sunset. Similar profiles were observed for mental activities and for
the desires to perform physical or mental work. In all cases, scores were higher in the daytime
than in the early morning and tended to fall in the evening; the effect of Ramadan was to
decrease daytime values and increase the evening value (Table 3.1).
46
The social activity scores showed a slightly different profile (Fig. 3.4, middle, and associated
statistics in Table 3.1). Activity was lowest in the morning and tended to rise throughout the
day. This profile was more marked in Ramadan, with peak activities in the evening (the
interaction between Time x Day being marginally significant). Sleepiness (Figure 3.4,
bottom, and Table 3.1) tended to show a profile that was the inverse of the other variables;
values fell in the daytime and rose towards evening. However, the evening rise in sleepiness
was much less marked in Ramadan, accounting for the significant interaction between Time x
Day.
3.3.2. Urine osmolality
On control days, the osmolality of the urine showed similar values throughout the daytime
and indicated (a normal degree of) mild dehydration (Figure 3.5). During Ramadan, by
contrast, whilst the values were very similar at 09:00 h, they increased throughout the day to
reach a value indicative of a greater degree of dehydration by 17:00 h. This difference in
profile between the two types of day accounts for the significant statistical differences that
were observed (Table 3.1).
3.3.3. Physical performance measures
Mean grip strength of both the dominant and non-dominant hands showed no significant
change between control days and Ramadan but a significant time-of-day effect, with higher
values at 17:00 h than 12:00 h (Table 3.1). When the two hands were compared (Figure 3.6),
the dominant hand was significantly stronger (FI, 19 = 14.6, P = 0.001). There was a
significant interaction between Hand x Occasion (F I, 19 = 5.3, P = 0.033), and Figure 3.6
47
indicates that the non-dominant hand tended to be slightly weaker in Ramadan - unlike the
dominant hand, which became slightly stronger.
The effects of the bout of exercise are summarised in (Table 3.1 and Figures 3.7-3.10).
Exercise always produced a highly significant increase in HR (about 75 beats/min, bpm) and
this was higher on control days (Figure 3.7). There was also a significant time-of-day effect,
the rise being greater at 17:00 h. However, the significant interaction tenn (Table 3.1)
indicates that the detailed changes were more complex; the rise in HR between 12:00 h and
17:00 h observed during Ramadan (about 7 bpm) was replaced by a slight fall (about 2 bpm)
on control days.
As indicated by Figure 3.8, a higher cadence was chosen at 17:00 h, though there was no
significant difference between Ramadan and control days.
48
4
t 8 3.5 00
.e-.;: 3
:e -< _ 2.5
5 ';l
E 2 ~
---Controls • D· Ramadan
1.5 +-------r----,----- -r----
09:00h 12:00h 17:00h 21:00h
Time of Day
--- Controls • 0 • Ramadan 3
.1 ~ _-J----~
= ---rJ 2.5 00 , .e-.• ~ .• 't
2 , < , -= , 'y
1 = 00 1.5
09:00h 12:00h 17:00h 21:00h
Time of Day
--- Controls • D· Ramadan 3
2.5
t 6 ~ 2 , , , ~
, 1.5 ,
= '~ .• J ..
0.5
0 -,--
09:00h 12:00h 17:00h 21:00h
Time of day
--,
Figure 3.4. Changes with time of day on control days and Ramadan in: top, Physical activity; middle, Social activity; bottom, Sleepiness. For explanation of Scores, see text.
49
Table .3.1. Statistical results from Analysis of Variance analyses.
Variable Ramadan vs. Controls
Subjective Estimates of Activity and Sleepiness:
Physical Activity
Mental Activity
Social Activity
Sleepiness
Desire for Physical Activity
Desire for Mental Activity
Urine Osmolality:
Physical Measures:
Grip Strength
Rise in HR with Exercise
Cadence
Lactate
RPE
F 1,19=0.1; P=0.80
F 1,19=2.9; P=O.ll
F1.19=0.1; P=0.78
FI,19=8.3; P=0.010
F1,19=2.7; P=0.12
F1,19<0.1; P=0.92
F I.19=5.3; P=O.033
F1. 19<0.1; P=0.82
Fl. 19=66.2; P<0.OOO5
F 1,19<0.1; P=0.86
F I, 19=15.9; P=O.OOI
Fl. 19=6.1; P=0.023
ANOVA Time of Day Interaction
F2.9, 54.9=83.3; P<0.0005 F2.5,46.?5.7; P=0.004
F 2.0,38.2=29.4; P<0.OOO5 F2.2,4u=1.7; P=0.19
F2.1,40.2=15.9; P<O.OO05 F]J,.u'5=2.7; P=O. 071
F 1.9,35.6=25.5; P<0.0005 F 1.8,34.3= 12.0; P<0.0005
F2.9,55.4=18.9; P<0.0005 F28,525=2.0; P=O.13
F2.6,49.,=19.8; P<O.OO05 F2. 7,51.8= 2. 5; P=O. 079
F1.8,33.8=16.3; P<0.0005 FI.8,34.6=44.4; P<0.0005
F 1.19=20.1; P<0.OO05 F 1,19<0.1; P=0.82
FI,19=6.6; P=0.019 FI,IF8.2; P=O.010
F 1.19=8.4; P=O.OO9 F 1.19=2.2; P=O.IS
F 1,1g=112.1; P<O.OO05 FI.lr9.1; P=0.OO7
F1.19=1.8; P=0.20 F 1,19=0.3; P=0.59
50
Comment
See Fig.3.4, top
Similar profile to Fig. 3.4, top
See Fig. 3.4, middle
See Fig. 3.4, bottom
Similar profile to Fig. 3.4, top
Similar profile to Fig. 3.4, top
See Fig. 3.5
17:00 h > 12:00 h
See Fig. 3.7
See Fig. 3.8
See Fig. 3.9
See Fig. 3.10
~Controls -[} • Ramadan .-. 900 ~ e 850 f:'-l Q
800 e "-' 750 ~ 0 700 ~
650 = ... -~ 600 -t--------r-------,---~------_____,
09:00h 12:00h 17:00h
Time of Day
Figure 3.5. Urinary osmotic pressure (mosmll) during control days and Ramadan .
..... Dominant Hand -[} • Non-dominant Hand 42 l ~
~ 40 .:: ....
38 ~ l 1 = e
36 .... 00 c..
?------------1 ... - 34 ~
Controls Ramadan
Occasion
Figure 3.6. Grip strength in dominant and non-dominant hands on control days vs. Ramadan.
51
.-. 90 = ... S ........
85 ,.Q 80 '-' ~ 75 = = 70 ... ~ 65 ~
~ 60
~Controls
I
Q-----
12:00h
-[} -Ramadan
I
_--.(:;1 -------- -------,
17:00h
Time of Day
Figure 3.7. Effects of exercise on rise of heart rate, HR, at two times of day on control days and during Ramadan.
~Controls -O-Ramadan 158
.-. =: 154 ~~~
... S ~ l _-"".-~ 150
c# CJ =: l~~~ ~
"C 146 = U 142 -,
12:00h 17:00h
Time of Day
Figure 3.8. Effects of exercise at two times of day on cadence (cycles/min) on control days and during Ramadan.
52
Also at 17:00 h, post-exercise lactate levels were higher (Figure 3.9). However, Ramadan
was associated with lower lactate levels in general (7.3 mM vs. 8.2 mM) and the significant
interaction term (Table 3.1) indicates a less marked exercise-induced increase at 17:00 h.
---Controls -O-Ramadan 10
9
8
7
6 i------------------------,-----------------------,
12:00h 17:00h Time of Day
Figure 3.9. Effects of exercise at two times of day on post-exercise lactate (mmol/l) on control days and during Ramadan.
Subjective estimates of exertion (RPE) did not show a significant time-of-day effect, but
mean values were higher in Ramadan than at other times (Table 3.1 and Figure 3.10).
...... Controls -O-Ramadan 13.0
12.5 o ---------~ ---~ 12.0
, ~ ,
11.5
11.0
12:00h 17:00h Time of Day
Figure 3.10. Effects of exercise at two times of day rating of perceived exertion (RPE) on control days and during Ramadan.
53
3.4. Discussion
The results indicate that Ramadan is associated with many changes to an individual's
sUbjective feelings (reasons for eating, general activity, and sleepiness), physiology (urine
osmolality and grip strength) and responses to physical activity (HR and blood lactate). Since
the results from the first and fourth weeks of Ramadan were not significantly different (and
so could be pooled for the statistical analyses), this indicates an important finding - namely,
that the subjects adjusted quickly (within the first week) to the demands of Ramadan and that
progressive deterioration did not take place. It is likely that such adjustment took place
almost immediately since the subjects had previous experience of fasting during Ramadan.
Other studies (reviewed in Reilly and Waterhouse, 2007) have found such a rapid adjustment.
A clear indication of the effects of daytime fasting can be seen by considering the intakes of
fluid and food after sunset. The osmolality of the urine provided evidence of progressive
dehydration during the course of the daytime (Figure 3.5) but, in the evening, all subjects
drank large amounts of fluid and ate a substantial meal (drink and food scores approaching
maximum values of 4.0). The reasons given for these increased intakes of fluid and food were
thirst and hunger and an acknowledgement of the need to recuperate from daytime fasting
(Figures 3.2, bottom, and 3.3). The main types of fluid drunk, water, fruit juice and milk
(Figure 3.2, top) would all aid rehydration, as would drinking less caffeine-containing
beverages (some fizzy drinks, tea and coffee) during Ramadan. This result has been observed
before (Waterhouse et al., 2008a) and it is possible that it is part of the culture of those living
in a hot country to take less frequently drinks that cause diaphoresis and diuresis, so reducing
dehydration.
54
Subjects went to bed later in Ramadan, and spent less total time in bed (Margolis and Reed,
2004; Roky et ai., 2003; Waterhouse et ai., 2008a, 2008b). However, the subjects in the
present study also tended to raise later in Ramadan, rather than earlier - possibly a reflection
of their lack of domestic commitments (they lived at home with parents). The later retiring
time might have contributed to the greater ease of getting to sleep in Ramadan. SUbjects ate
meals in the evening that were larger than normal and also ate just before retiring, claiming
that this helped them get to sleep. The quality of sleep has been shown to change in Ramadan
(Roky et aI., 2003) but possible interactions between time of retiring, amount and timing of
food eaten and quality of sleep need further investigation.
Subjects felt sleepier in the daytime but this increase did not extend into the evening (Table
3.1). Even so, they did not nap during the daytime, citing "too busy" as the reason (Figure
3.1). This result differs from some that have been published (Margolis and Reed, 2004),
including our own (Waterhouse et aI., 2008a, 2008b), and reflected the individual's full
commitments at the Sports Academy, with little opportunity to catch up on lost sleep during
the daytime. A lack of standardisation of the populations studied here and in the literature (in
terms of age, family and work commitments, etc.) probably contributes to the variation in
results.
As a result of these changes in fluid and food intakes in the daytime and altered sleep at
night, subjects would have been showing effects of sleep, fluid and food deprivation. This
combination of factors would be predicted to have negatively affected aspects of mood and
mental performance, and some types of physical performance (Reilly and Edwards, 2007;
Reilly and Waterhouse, 2007; Waterhouse et aI., 2001). Subjective estimates of the amounts
55
of physical and mental performance carried out, and the desire to undertake them (Table 3.1
and Figure 3.4, top), all showed that Ramadan was associated with decreased activities in the
daytime but increased values in the evening after sunset. Such results have been found and
discussed previously (Kadri et al., 2000; Karaagaoglu and Yucecan, 2000; Roky et a/., 2000;
Waterhouse et al., 2008a, 2008b). The current results can be interpreted as further evidence
of the changes to daily life produced by the demands of Ramadan as well as a validation of
the present protocol and subjects. Social activities also changed in Ramadan, being higher
throughout the daytime as well as the evening (Figure 3.4, middle); higher daytime values in
Ramadan differed from previous findings (Waterhouse et a/., 2008a, 2008b). This difference
possibly reflects the fact that the subjects were younger and lived at home with few domestic
responsibilities, previous studies being upon individuals who were housewives or students
living alone.
The results of Figure 3.6 support the view that physical activity is changed in Ramadan, but
the effects are complex. As expected, the dominant hand produced greater strength than did
the non-dominant hand, and afternoon values were higher than those produced at noon.
However, there was a difference between the two hands, the non-dominant hand appearing to
be more susceptible to negative effects of Ramadan. A difference between the dominant and
non-dominant hands has been observed before using a task requiring hand-eye co-ordination
(Edwards et al., 2008). This difference between the two hands might reflect the relative roles
played by neural and muscular components and their susceptibilities to fasting and sleep loss,
but this possibility needs further investigation.
56
Time-of-day effects were present in the rise of HR after exercise, the chosen cadence for the
exercise and the post-exercise blood lactate level (Table 3.1 and Figures 3.7-3.9,
respectively). It should be remembered that the circadian rhythm of HR, which peaks around
the early afternoon, is earlier than that of core temperature, which peaks in the late afternoon
(Reilly and Brooks, 1982, 1986); as a result, the HR in the current study would have been
around its peak at 12:00 h but decreasing by 17:00 h. By contrast, the rise in cadence between
12:00 h and 17:00 h is commensurate with a rise in core temperature and effects of this rise
upon metabolic activity (Thomas and Reilly, 1975); such a rise in metabolic activity between
12:00 h and 17:00 h could also explain the rise in blood lactate (Forsyth and Reilly, 2004,
2005).
Ramadan caused changes in the mean rises in HR (Figure 3.7) and blood lactate (Figure 3.9)
in response to exercise, but whether these changes arise from the effects of sleep loss and/or
the metabolic consequences of dehydration and lack of food intake and/or changes in
motivation, for example, cannot be determined from the present results. These factors are
likely to interact with one another. The lower rise of HR in Ramadan is compatible with a
lower sympathetic drive, commensurate with energy disturbances, during Ramadan, and has
been observed also following sleep deprivation (Reilly and Edwards, 2007). By contrast, the
greater rise in HR at 17:00 h compared with 12:00 h in Ramadan (Figure 3.7) might reflect
the need, as the length of fasting increases, for an increased HR to maintain blood pressure in
the face of greater dehydration and falling venous return. The lower lactate values when
fasting has been attributed to a greater use of lipids as fuel at this time (Benaji et aI., 2006;
Leiper et aI., 2003; Reilly and Edwards, 2007; Reilly and Waterhouse, 2007; Roky et aI.,
2004).
57
The finding that the perception of load was increased (Figure 3.10) in spite of decreased rises
in HR and lactate accords with the subjective estimates of a decreased amount of physical
work actually performed, and also wished for, in the daytime (Figure 3.4, top and Table 3.1).
Also, the statistically significant interactions between Occasion (Ramadan vs. control days) x
Time of day for blood lactate and rise of HR (see Table 1 and Figures 3.7 and 3.9) suggest
that the effects of Ramadan (whatever their cause) worsen as the day proceeds. These greater
"stresses" when performing physical activity later in the day are in contrast to the result that
is normally found, where physical performance at 17:00 h is better than at 12:00 h and less
demanding physiologically, biochemically and mentally (Reilly and Edwards, 2007; Reilly
and Waterhouse, 2007; Reilly et at., 1997).
3.5. Conclusions and Limitations
In summary, Ramadan makes many demands upon those involved, and is responsible for
changes in sleep, daytime sleepiness, actual and desired behaviour, and physical
performance. The changes cause a decrease in both the amounts of daytime activity actually
performed and in the amounts desired. There is also clear evidence that a given bout of
physical performance at the end of the daytime fast places a greater burden on the body, and
is perceived as being more demanding than is the same bout of activity performed earlier in
the daytime. These changes from control days take place within the first week of Ramadan,
and further deterioration later in Ramadan does not seem to occur. Individuals recuperate
after sunset by eating and drinking more, and their intake of fluid tends to exclude drinks
which would promote further dehydration. There are clear implications from these results for
individuals performing physically-demanding tasks late in the day in Ramadan, when effects
due to fatigue and dehydration will be more marked.
58
3.5.1. Limitations of the study
The first limitation is that the protocol does not enable possible links between the various
changes to be determined. For example, it is reasonable to suppose from the scientific
literature that the restrictions of food and fluid intake will be a causative factor in
performance and mood deterioration (Bellisle, 2002; Kadri et al, 2000; Karaagaoglu and
Yucecan, 2000; Keys et al. , 1950; Khammash and AI-Shouha, 2006; Kleiner, 1999; Leiper et
al. , 2003; Maughan, 2003; Oliver et al., 2006; Ramadan et al. , 1999; Roky et al. , 2000,
2004; Yacine et al., 2007) but additional effects due to sleep loss (Dinges, 1995; Kleitman,
1939; Margolis and Reed, 2004; Neri et al., 1997; Roky et al., 2001, 2003; Waterhouse et al,
2001) and/or metabolic changes (Bogdan et al., 2001; Bouchared and Touitou, 2001;
Consolazio et al, 1967; Karaagaoglu and Yucecan, 2000; Qujeq et al., 2002) cannot be
discounted. Also, establishing associations between the various changes (by determining
correlations between pairs of variables, for example) does not enable causal links to be
established. The only way in which causal links can be established is by the use of an
intervention protocol in which some of the variables (amount of sleep taken, for example) are
kept constant and others (length of fasting, for example) are changed systematically. Such an
intervention study will be described in Chapter 6.
A second limitation is that, even though the results from this field study have extended those
from previous work by our group (Waterhouse et al., 2008a, 2008b) and shown that physical
performance was decreased in Ramadan when measured objectively as well as subjectively,
the number of variables measured was comparatively limited. A fuller understanding of the
changes in Ramadan requires investigations using a broader range of measurements of
physical activity as well as measurements of mental performance. Moreover, making
measurements at more times of day (including after the day's fast has ended) is desirable.
59
Such additions to the protocol are difficult to perform in the field, and they require the studies
to be performed in the laboratory. Such studies will be described in Chapters 4 and 5.
60
Chapter 4
Laboratory-based studies
I. Introduction to Laboratory-based
Studies
II. A Pilot Study of Changes in Body
Mass and Physical Performance
During One Day of Fasting
\~J
~t~ JMU
Liverpool John Moores University
I. Introduction to Laboratory-based Studies
The results from the field study (Chapter 3) extended those from previous work by our group
(Waterhouse et aI., 2008a, 2008b) and showed that physical perfonnance was decreased in
Ramadan when measured objectively as well as subjectively. Even so, the number of
variables measured was comparatively limited, and a fuller understanding of the changes
during the course of the day in Ramadan requires investigations using a broader range of
measurements. Previous work (Chapter 3 and Waterhouse et ai., 2008a, 2008b) had also
shown that the changes observed were not progressive during the month of Ramadan,
differences from control days not being statistically significantly different during the first and
fourth week of fasting. This result raises the possibility that the effects of fasting seen in
Ramadan might be simulated by a period of fasting lasting less than four weeks, even a single
day.
Making further measurements in the field is difficult, and it is not always possible to perfonn
them in a laboratory, as was the case in the study of Chapter 3; one way to overcome such a
problem might be to perform the whole study in a laboratory, simulating the demands of
Ramadan but for a shorter period of time, a day rather than a month. To investigate if such a
Protocol would give results of value to an understanding of the changes in Ramadan has been
the aim of the pilot study and the study described in Chapter 5. However, before describing
these studies, it is necessary to compare the advantages and disadvantages of field- and
laboratory-based work.
62
4.1 Advantages and disadvantages of field- and laboratory-based studies
The advantage of a field study is that it is "real" rather than artificial and, for studies of
Ramadan, can investigate any progressive changes during the course of the 4 weeks of
fasting. In practice, however, a field study also results in an increased amount of "noise".
Such noise results from changes to individuals' daily lifestyles (as a result of domestic and
work-related issues) and changes in the weather, for example. There is also a limit to the
number of measurements that can be made in such circumstances, due to lack of availability
of suitable apparatus and the time taken to perform the tests. The problem can be solved if a
fully equipped laboratory is readily available (as was the case in the study of Chapter 3,
Waterhouse et at., 2009), but this is not always possible.
If the study takes place in a laboratory, by contrast, some of the advantages are:
There is more control of the environment.
More detailed tests can be carried out (though their application to "real-world" tasks
can always be questioned).
The timing of the tests is easier to control.
It is easier to check that the subjects are compliant.
However, one problem that arises when a more detailed study is performed in the laboratory
is that of the time required to perform the tests. In practice, therefore, subjects in such studies
tend to be restricted in the activities they can pursue when not being tested (needing to be
close to the laboratory and to have sufficient time to perform the tests). Also, the
investigations cannot last for a whole month (as is the case when effects of Ramadan are
being considered) but are restricted to a single day only. This does have a potential
disadvantage that adjustments of sleep patterns and the types and timing of food and fluid
63
intakes are not fully comparable in a short-term laboratory-based study to the longer-term
changes adopted in Ramadan. Even so, the results from both types of study can be valuable
when compared and, in practice, the results from field- and laboratory-based studies
complement each other.
4.2 Rational for the three laboratory-based studies
Three laboratory-based studies have been performed. Of these, the first two (the pilot study
and the study to be described in Chapter 5) were designed to investigate the value of a single
day of fasting in the laboratory as a viable tool for investigating changes that occur during
Ramadan. The second study (Chapter 5) was more elaborate, recording more variables at
more time-points, than the pilot study. In both studies, subjects were studied on two
occasions, a control day (normal food and fluid intakes) and a fasting day (food not being
allowed during the daytime). Subjects were free to choose their activities between testing
times, their sleep times, and food and fluid intakes before 07:00 h, mimicking the conditions
that exist in Ramadan. However, even though long-term changes in sleep and foodlfluid
intake patterns would be absent from such a protocol, previous work (Waterhouse et al.,
2008a, 2008b and Chapter 3) had indicated that such effects were absent.
These two studies confirm the findings of the field study, namely that physical performance
deteriorated during fasting, but it was unclear, particularly from the field study, if the
decrements in perfonnance were due to food and fluid restriction and/or sleep loss. In the
third laboratory-based study (Chapter 6), an attempt was made to resolve this ambiguity. The
study was an intervention design that investigated the effects of timed amounts of fasting
upon a variety of variables (mood, mental performance, physical performance, activity and
64
dehydration) but when sleep was controlled. This protocol enabled not only effects of specific
durations of food and fluid restriction to be investigated but also possible confounding
factors, such as changes in ambient temperature and sleep times, to be controlled.
The results from the three laboratory-based studies can be compared with those from the
field-based study and published work, to consider the extent to which the effects of Ramadan
can be replicated in short-term studies in the laboratory.
65
II. A Pilot Study of changes in Body Mass and Physical Performance during One Day of
Fasting
This pilot study was perfonned in the UK in November, 2007-March, 2008. The rationale for
the study, described above, was to investigate, in more detail than can conveniently be
undertaken in the field, changes to a small group of variables during the course of a single
day of fasting from 08:00-16:00 h. The variables chosen for investigation were directly based
on those measured in the field study (Chapter 3). It was hypothesised that changes observed
during the course of fasting for a day would closely mirror those observed in the field in
Ramadan; that is, there would be a fall in body weight, deterioration in physical perfonnance,
and a rise in urine osmolality as the subjects became dehydrated.
4.3. Methods
4.3.1. SUbjects
Twelve subjects (8 males) aged (mean, SD) 26.25, 7.66 years and height 1.74, 0.08 m took
part in the study. Females were studied at all stages of their menstrual cycles. Subjects were
recruited from the student population at Liverpool John Moores University using day-to-day
interactions within the campus community and word-of-mouth. Subjects volunteered to
participate in the study with the understanding that participation was not monetarily
compensated and they could withdraw at any time without giving any reason.
The general aims and details of the protocol were explained to them (but detailed reasons for
the study were not given), and any questions were answered. Volunteers were given a
document outlining these procedures and methods and were asked to read and sign a consent
66
document before being allowed to further participate. The study had been passed by the
University Ethics Committee.
4.3.2. General design
Before the two experimental days, the subjects were required to come in for a familiarization
session. During this session, subjects were informed of the measurements that were going to
be made and were able to use the apparatus involved. They were also told which
experimental days would be the control and fasting days, the order of which was randomised
for the group as a whole.
During each of the two experimental days, subjects had to attend the laboratory three times,
at 08:00, 12:00 and 16:00 h. On each occasion, subjects' body mass was measured and then
they rested for about 30 min; during this time, any problems with the protocol were discussed
and the apparatus for measurement (see below) was attached. At the end of this period,
resting heart rate and grip strength were measured. Subjects then gave a urine sample.
Subjects were required to cycle for 5 minutes on a cycle ergometer (Ergo-bike Medical 8,
Daun electronic company, Germany) at a constant load of 70 watts. The rate of pedalling was
left to each subject to decide upon. Heart rate was taken every minute during the exercise as
well as immediately after exercise. After a recovery period of about 10 min, during which the
apparatus was removed, subjects were free to leave the laboratory until the next test session.
67
4.3.3. Measurements made
At each of the three times on the two experimental days, the following measurements were
made:
4.3.3.1. Body mass
Body mass was measured to the nearest 0.1 kg were recorded using analogue Seca scales
(Seca Ltd., Birmingham, UK). Before and after the bout of exercise.
4.3.3.2. Physiological Variables
The variables measured were grip strength (left and right hand) and heart rate. Grip strength
was measured by a Handgrip Dynamometer (TRK51 06, T AREK Scientific Instrument Score,
Japan). Right and left grip strengths were measured alternately, to limit the effects of fatigue.
The peak values and averages of the grip strengths were taken.
Heart rate was monitored by a monitor (Polar, Kempele, Finland) strapped to the chest and a
data logger attached to the subject's wrist.
For urine osmolality, the bladder was emptied completely and an aliquot (50 ml) of the
sample was stored at 1 DoC until later analysis for osmolality (Osmocheck pocket pal OSMO,
Vitech Scientific Ltd, Japan). This variable was used as a measure of general dehydration.
68
4.3.4. Statistics
Analysis of variance with repeated measures was used. The main factors were Day (2 levels,
Controls vs. Ramadan) and Time of Day (3 levels). The additional factors Hand (dominant
vs. non-dominant) for grip strength and Exercise (before vs. after) for heart rate, HR, were
used in 3-factor ANOVAs. Greenhouse-Geiser corrections were used, and significant
differences within the main factors were assessed using Bonferroni corrections.
The SPSS package, version 14, was used. Significance was set as P<0.05, though occasions
where 0.05<P<0.1 0 have been reported as "marginally significant". Exact P values have been
given; results given as "0.000" in the statistics output have been reported as "<0.0005".
4.4. Results
4.4.1. Body Mass.
Body mass fell during the daytime in fasting and indicated the loss of about 1 litre (1 kg) of
fluid (Figure 4.1). Body mass showed no significant effect of Day (F I, II = 2.04, P = 0.18) but
a highly significant effect of Time of day (FI.2. 12.9 = 19.73, P<0.0005) and a significant
interaction (FI.2. 13.4 = 17.39, P<0.0005) due to the decreasing body mass during the course of
the day only when fasting (mass remaining similar on the control day).
69
~ • Control DFasting
80 ~ --...... 60 -= ~ •• ~ 40
~ "0 20 Q
== 0
08:00 12:00 16:00
Time of Day
Figure 4.1. Body mass. Mean and SE. Closed bars, Control day~ open bars, Fasting day.
4.4.2. Urine osmolality
The osmolality rose on the fasting day but not on the control day (Figure 4.2). There was no
significant effect of Day (F 1, 11 = 2.04, P = 0.18) but there was a significant effect of Time of
day (F1.5, 16.3 = 6.54, P = 0.013) and a significant interaction between Day x Time of day (F1.7,
18.4 = 7.07, P = 0.007), because urine osmolality increased during the daytime in the fasting,
but not the control, day.
900
850
800
750
700
650
600
08:00
• Control DFastin~
12:00 16:00
Time of Day
Figure 4.2. Urine osmolality. Mean and SE. Closed bars, Control day; open bars, Fasting day.
70
4.4.3. Grip strength
For the non-dominant (left) hand, there was no significant difference for Day (F I, II = 0.414, P
= 0.53) or Time of day (F1.8, 19.8 = 1.33, P = 0.29), and no significant interaction (FI.5, 16.8 =
0.60, P = 0.52) (Figure 4.3). For grip strength of the dominant hand, there was a marginally
significant difference for Day (F I, II = 4.03, P = 0.070) but no significant effect of Time of
day (FI.7,19.1=1.34, P = 0.28) or interaction (F 1.9,2 1.3 = 2.23, P=O.13) (Figure 4.4). When results
from the two hands were compared, the right hand (dominant hand) was significantly
stronger (F I, II = 39.00, P<0.0005) and there was a marginally significant interaction between
Hand x Occasion (F I, II = 3.62, P=0.083) because the fall in grip strength of the dominant
hand during fasting was more marked than that of the non-dominant hand.
~ -Control CFasting ~ 40
---= 30 ..... ~ = 20 ~ .....
r.I'J. 10 Q. .... ..
~ 0
08:00 12:00 16:00
Time of Day
Figure 4.3. Grip strength, left (non-dominant) hand. Mean and SE. Closed bars, Control day; open bars, Fasting day.
71
~
ell -Control CFasting
~ '-"
40
-= 30 ..... ell
= 20 e ..... 10 rIJ. Co
0 .... .. ~ 08:00 12:00 16:00
Time of Day Figure 4.4. Grip strength, right (dominant) hand. Mean and SEe Closed bars, Control day; open bars, Fasting day.
4.4.4. Exercise
There was a rise in HR produced by the 5 min of exercise (FI.8, 20.2 = 7.19, P = 0.005) but this
rise was not significantly different between the control and fasting days (F I, II = 0.27, P =
0.62) or between the three times of measurement during the course of the day (F 1.9,20.5 = 0.09,
P = 0.90). There was one significant interaction, that between the time of day when exercise
was taken and whether it was a control or fasting day (F1.7, 18.7 = 4.74, P = 0.026): for the
control day, the HR after exercise increased as the day progressed whereas the opposite
change took place during fasting (Figure 4.5).
= ~ 120 .... _Control CFastin~
S = 100 .... an S 80 .............. ~e 60 .. ~ ~ ~ 40 ~ .... ~ ~ 20 ~ ~ 0 == ~
08:00h 12:00h 16:00h
Time of Day
Figure 4.5. Heart rate at the end of the 5-min cycling. Mean and SE. triangles Control days; Squares, fasting days.
72
4.5. Discussion
The results showed that body mass fell (Figure 4.1) and urine osmolality rose (Figure 4.2),
during the fasting but not the control day. These results would be predicted from basic
physiology, where dehydration leads to conservation of body fluid and production of
concentrated urine. The scientific literature also supports these findings. Thus, body mass has
been found to decline during Ramadan and other diet-restriction strategies (Hall and Lane,
2001; Ramadan et aI., 1999), and urine osmolality, normally in the range 400-600 milli
osmoles (mOsm), rises towards 900 mOsm as the degree of dehydration increases (Ramadan
et al., 1999). Such results have been found previously in Ramadan (Reilly and Waterhouse,
2007) and the rise in urine osmolality also agrees with the results found in the field study
(Chapter 3).
Grip strength, a simple and proven test of maximal muscular strength, has been used in many
diet-restriction experiments (Keys et al.,; 1950Consolazio et al., 1967). Even so, in the
current experiment, grip strength (Figures 4.3 and 4.4), showed comparatively little change.
There was, however, a marginal decline in grip strength of the dominant hand on the fasting
day, and interaction between Hand x [Control vs. Fasting]; both these results point to a
greater deterioration of grip strength of the dominant hand during fasting. This greater
decrement might reflect a more sophisticated control mechanism, involving neural and
muscular elements, in the dominant hand (see discussion in Edwards et al., 2009).
For resting heart rate also, no differences between control and fasting days were observed
(data not shown). However, HR immediately after exercise rose during the course of the day
on the control day but fell on the fasting day (Figure 4.5). Higher heart rates after exercise
73
during the course of control days would be predicted as a result of the circadian rhythm of
heart rate at rest and in exercise (Minors and Waterhouse, 1981); lower post-exercise values
during the course of the fasting day accords with the view that physical performance
deteriorates with dehydration (Reilly and Waterhouse, 2007).
One explanation of the comparatively few significant differences between control and fasting
days is that grip strength and heart rates following a 5-min bout of exercise are not
sufficiently sensitive markers to pick up the changes that might be observed during a single
day of fasting. In support of this view, other studies have indicated that physical performance
is quite resilient in the face sleep loss or food and fluid restriction, provided these are limited
in extent (Reilly and Waterhouse, 2007, 2009; Reilly et al., 1997; Waterhouse et al., 2001).
What this pilot study does show is that it is possible, in a laboratory-based protocol lasting a
single day, to mimic at least some of the effects of fasting in Ramadan. Even so, it is clear
that a wider variety of markers of performance would be advantageous. These can include
further measures of the response to a bout of exercise and objective estimates of mental
performance in addition to the subjective measures that were obtained from the questionnaire
used in the field study (Chapter 3). Further, if recuperation in the evening from fasting is to
be studied, an important response in Ramadan (Waterhouse et aI., 2008a, 2008b and Chapters
2 and 3), then a further time-point, sometime in the evening, needs to be measured.
It seems reasonable to conclude that the current protocol, with the appropriate modifications
just described, can be used as a tool to assess in more detail the responses to a single bout of
daytime fasting. Such a study will form the basis of Chapter 5.
74
Chapter 5
A More Detailed Study of Changes in
Performance Produced by One Day of
Fasting
\~~
~t~ JMU
Liverpool John Moores University
5.1. Rationale
The results from the pilot study (Chapter 4) indicated that some of the changes found in field
studies of Ramadan (Chapter 3 and Waterhouse et aI., 2008a, b) could be duplicated in the
laboratory in a protocol involving one day of fasting. For example, urine osmolality showed
changes indicating the development of dehydration during the daytime. It was concluded that
such results indicated that the laboratory-based experiment and the protocol used provided a
useful tool for assessing some of the changes produced by fasting and changes of the sleep
wake cycle in Ramadan. By contrast, some of the measurements indicated rather small
changes due to fasting, including grip strength and the response of heart rate to a 5-min bout
of exercise. It was suggested that such a lack of change in measures of objective performance
might indicate that the measures used were not sufficiently sensitive to the effects of only one
day of fasting. Another possible problem was that measurements were made only until the
end of fasting (16:00 h), as a result of which any recuperation, as previously observed in the
field studies, could not be investigated.
The aim of this study is to build upon the results of the pilot study (Chapter 4) and to
InCorporate two improvements: additional measurements of performance and more frequent
times of measurement. These times would span a wider portion of the waking period,
including four times per fasting period, rather than three, and a set of measurements after the
end of the fast and before retiring, so bringing the protocol closer to those of the field studies
of Ramadan (Chapter 3 and Waterhouse et aI., 2008a, 2008b).
76
It is hypothesised that daytime fasting will lead to dehydration and will cause a decrement in
performance, measured both subjectively and objectively, in comparison to the control days,
when there are no restraints on fluid and food intakes.
5.2. Methods
5.2.1. Subjects
Eighteen male subjects, Liverpool John Moores University undergraduates with an age range
of 18-21, were recruited by word of mouth for the study. None was Muslim and none had
previously participated in food/fluid-restriction study. The experiments were completed in the
months January and February, 2009 and had previously been approved by the University
Ethics Committee.
5.2.2. Protocol
Subjects initially underwent a familiarisation session in which all aspects of the testing were
explained, including the two conditions (fasting and non-fasting), and the dates on which the
two conditions were to be performed. The various tests were described and subjects were
required to practise them, to reduce learning effects during the main part of the experiment.
Any questions were answered and then the subjects were required to sign informed consent
forms.
The main experiment (begun at least one week after the familiarisation session) was in two
parts: a non-fasting (control) day and a fasting (intervention) day. The order in which the two
experimental days took place was randomly selected by the experimenters, but the subjects
77
knew of this order at least a week in advance. This arrangement gave them the opportunity to
eat/drink prior to sunrise (07:00 h) on the testing day and to go to bed/rise earlier if they
wished to do so.
On both experimental days, subjects were studied five times, at 09:00, 12:00, 15:00 and 18:00
h and on retiring to bed. On the control (non-fasting) day, subjects were free to choose when
to sleep, and what and when to eat and drink. On the fasting day, subjects were free to choose
when to sleep and what to eat and drink before 07:00h and after 18:00 h. Food and fluid
intake were prohibited between 07:00 hand 18:00 h but subjects were free to nap if they
choose to do so.
On each experimental day, subjects attended the laboratory at 09:00, 12:00, 15:00 and 18:00
h, to perform a series of tests and give a urine sample; they also answered the questionnaire
again at home, when choosing to retire to bed at the end of the day. The tests and samples
were given in the following order: urine sample (analysed for osmolality, see Chapters 3 and
4); questionnaires whilst sitting quietly (used previously, see Chapter 3), hand grip strength
(dominant hand only, 3 times each measurement, as performed previously, see Chapters 3
and 4); vertical jumps (performed 3 times; this is an additional measurement); accuracy at
throwing darts (as used in previous studies, Waterhouse et ai., 2008a, but an addition to this
type of study) and the Stroop test (a measure of mental performance that also is new to this
type of study). These tests are now described in more detai1.
78
5.2.3. Measurements made
5.2.3.1. Questionnaires
Subjects were required to give information about their daily activities and feelings over the
course of the day. The information was gained from a questionnaire which the subjects
completed five times during each of the two days they were being investigated. The
questionnaire is shown in Appendix 4.1.
The five times they answered the questionnaire were (l) at 09:00 h, which reflected activities
after waking, (2) at 12:00 h, which reflected morning activities, (3) at 15 :00 h, which
reflected activities in the early afternoon, (4) at 18:00 h, which reflected late afternoon
activities and (5) on retiring to bed (designated 24:00 h in the Figures), which reflected
evening activities after breaking the fast.
For some of the variables (the reasons for drinking/not drinking and eating/not eating), the
"fraction of possible occasions" was calculated for the group. This calculation was
performed as follows. Suppose, for example, that only 12 of the 18 subjects drank on a
particular occasion and that 8 of these gave the reason "Thirsty". This means that the fraction
of possible occasions that Thirsty was chosen was 8/12, that is, 0.67. Suppose, further, that,
of the 6 who did not drink, 2 gave the reason "Too busy". This means that the fraction of
possible occasions that Too busy was chosen was 2/6, that is, 0.33.
79
5.2.3.2. Physiological and performance tests
A. Urine osmolality
This provides a measure of dehydration of the body. The urine sample was collected into a
plastic pot and stored at SoC until analysis. For the analysis, a 5 ml aliquot was taken and its
osmolality measured (Osmocheck Pocket Pal OSMO, Vitech Scientific Ltd, Japan).
B. Stroop test
The test used was the Colour-Word Stroop Test (CWST). It is a test that assesses working
memory and attention. Therefore, it would be expected to show a daily rhythm peaking
around noon (Folkard, 1990; Waterhouse et al., 2001) and, though it has not been used before
in studies of Ramadan, might be expected to show deterioration due to restrictions of food
and fluid intakes.
The test consisted of the subject viewing 20 separate cards. Each had a colour, "red",
"orange", "green" or "brown" typed on it in one of these four colours. However, in many
cases, the word was typed in a colour that was different from the meaning of the word - the
word "orange" might be typed in green, for example. The participant was required to state the
colour in which the word was typed, not the name of the colours itself. (In the example given,
the correct answer would be "green" rather than "orange"). Incorrect answers had to be
corrected by the subject. The total time taken to answer all 20 questions correctly was
recorded on a stopwatch.
80
C. Throwing darts
Throwing darts can be used as a model for investigating circadian and time-awake factors
that influence motor performance (Edwards et al., 2007). The subjects threw darts at a
circular target (20 cm diameter) placed on the floor at a distance of 2.37 metres; the target
consisted of 10 concentric rings of diameter 2 cm, 4 cm, 6 cm, ...... 20 cm (See Appendix,
5.1). The subjects had 20 attempts to throw the dart as close to the target's centre as possible.
After each throw the score for each dart was measured and then the dart was collected for the
next throw. The score was determined as follows: a dart in the innermost ring scored 10
points, and darts in the other rings moving out from the centre scored 9, 8, 7 ... 1 point,
respectively. When a dart missed the target, the score was recorded as zero (a "miss"),
regardless of the size of the miss.
In the analysis, the results from the first and last three darts were ignored (though the subjects
did not know this when they were performing the test), due to possible effects of "getting my
eye in" and "nearly finished". The total score for the 14 darts, the number of misses, and the
mean score per hit (ignoring the misses) were used as measures of throwing accuracy
(Edwards and Waterhouse, 2009; Edwards et ai., 2007).
D. Hand grip strength
Only the dominant hand of each subject was investigated using a dynamometer (Handgrip
Dynamometer TRK5106. Jump MD, TAREK Scientific Instrument Score, Japan). The
subject recorded grip strength on 3 occasions separated by 10-sec intervals, the maximum of
the three values being recorded. This is a test of muscle strength using a comparatively small
group of muscles.
81
E. Jump height
The jump test is a further example of a test of physical strength but, unlike grip strength,
involves the integrated actions of several groups of muscles. Subjects performed 3 maximal
vertical jumps using the "stand-and-reach" method (Reilly et al., 1997). Subjects stood side
on to a wall and reached up with the right arm, which was next to the wall. Keeping the feet
flat on the ground, the wall was marked by the tip of the fingertips, onto which chalk powder
had been placed. The subjects then jumped vertically as high as possible using both arms and
legs to assist in projecting the body upwards. The wall was touched at the highest point of the
jump. The difference in distance between the standing height and the jump height was the
height jumped. The best of three attempts was recorded.
After the vertical jump tests had been completed, subjects were free to leave the laboratory
and continue their activities until the next visit to the laboratory. Subjects varied in their
experience of having throwing darts before the experiment, but none of them had any
previous experience with regard to answering the questionnaires or performing the other
tests.
5.2.4. Statistical analysis
The data were analysed by means of the Statistical Package for Social Sciences (SPSS) for
windows (version 14). For most data, two-way ANOVA with repeated measures was used.
The main factors were Day (2 levels, Controls vs. Fasting) and Time of Day (4 or 5 levels,
pre-09:00, 12:00, 15:00, 18:00 and post-18:00h for the results from the questionnaires). When
fractions of possible occasions were compared, the data were Arcsin-transformed before
ANOVA (a standard method used to make the data distributed more normally). Greenhouse-
82
Geiser corrections were used, and significant differences within the mam factors were
assessed using Bonferroni corrections. To compare nominal data (if subjects chose to eat or
drink before sunrise, for example) the McNemar and Cochran tests were used.
Correlations between variables were assessed using the method of Bland and Altman (1995),
a method which corrects for multiple pairs of values being obtained from each subject.
Exact P values are reported; significance was set as P<O.05, though occasions where
O.05<P<0.10 have been reported as "marginally significant".
5.3. Results
5.3.1. Results from questionnaires.
5.3.1.1. Drinking
Comparisons between drinking and eating on the control and fasting days during the daytime
were not made, since they were determined by the requirements of the protocol. However, it
was possible to compare results before and after the period of fasting, to investigate
preparations for, and recovery from, the period of fasting.
The number of subjects drinking or not drinking before 09:00h was compared on control and
fasting days (Figure 5.1). There was a significant increase in the number of subjects drinking
before the day of fasting (13 out of 18, compared with only 6/18 on the control day,
P=O.OI6).
83
The reasons given for drinking are shown in Figure 5.2. The four reasons were cited by
different numbers of subjects on both control (P=O.OlO) and fasting (P<O.OOOS) days.
"Thirsty" was cited most frequently on both types of day; "Preparation" was cited only on
fasting days, even though this difference was not significant (P=0.2S) due to the small sample
size.
There were too few occasions of "Not drinking" for statistical analysis of the reasons given to
be performed.
All subjects drank after 18:00 h on both days. The reasons given for drinking are shown in
(Figure 5.3). The four possible reasons were cited by different numbers of subjects on both
control (P<0.0005) and fasting (P<0.0005) days. "Thirsty" was cited most frequently on both
types of day; "Recover" was cited significantly more frequently on fasting days (P=0.002).
~ 14 -Control CFasting ~ = 't:.;
12 ~ = .~.-..Q a.. ="t:S 10 ~ .....
c.. 0 o = a.. ...... 8 ~ ~
..Q = E:.; 6 = = Z .... a.. 4 "t:S
Drink Not Drink
Time of Day
Figure 5.1. Number of subjects drinking/not drinking before 09:00 h
84
-Control o Fastin2
Thirsty Sociable Health Prepare
Type of Reason
Figure 5.2. Reasons for drinking before sunrise. For calculation of "Fraction of Possible Occasions", see Methods.
-Control ~ 1
CFastine -,.Q •• 0.8 11.)
11.)
Q 0.6 ~
c... Q 0.4
= Q 0.2 •• ..... CJ
e 0 ~
Thirsty Sociable Health Recover
Type of Reason
Figure 5.3. Reasons for drinking after sunset. For calculation of "Fraction of Possible Occasions", see Methods.
85
5.3.1.2. Eating
The number of subjects eating or not eating before 09:00 h was compared on Control and
Fasting days (Figure 5.4). There was an increase in the number of subjects before 09:00 h on
the day of fasting (12/18 compared with 7/18 on the Control day) but this difference was not
significant (P=0.125).
~ 15 = -Control CFasting .• ....
13 = ~
~ ~ 11 ~ = :c-~ = = fI.l ~ 9
t.,. ..... o 0 7 ... ~
~ .c a 5
= Z Eat Not Eat
Time of Day
Figure 5.4. Number of subjects eating Inot eating before 09:00 h.
The reasons given for eating are shown in Figure 5.5. The four reasons were cited by
significantly different numbers of subjects on both control (P<0.0005) and fasting (P = 0.015)
days. "Hungry" was cited most frequently on both days; "Prepare" was cited only on fasting
days, even though this difference was not significant (P = 0.125).
There were too few occasions of "Not eating" for statistical analysis of the reasons given to
be performed.
86
1.2 -Control o Fasting ~ -:e 1.0 fIJ fIJ fIl £ § 0.8
""'" ... Q fIl 0.6 fIJ = = CJ Q CJ 0.4 ~O E 0.2
~ 0.0
Hungry Sociable Prepare Health
Type of Reason Figure 5.5. Reasons for eating before sunrise. For calculation of "Fraction of Possible Occasions", see Methods.
The reasons given for eating after 18:00 h are shown in Figure 5.6. The four reasons were
cited by significantly different numbers of subjects on both control (P< 0.0005) and fasting
(P< 0.0005) days. "Hungry" was cited most frequently on both days; "Recover" was cited
significantly more frequently on fasting days (P = 0.002).
~ 1.2 -..c -Control o Fastine ...
1.0 fIl fIl Q fIl 0.8 ~ = Q c.. ... 0.6 Q fIl fIl ~
0.4 = ~ .S 0 ~ 0.2 CJ
= 0.0 a. ~
Hungry Sociable Recover Health
Type of Reason
Figur~ 5.6. Reasons for eating after sunset. For calculation of "Fraction of Possible OccasIons", see Methods.
87
5.3.1.3. Physical activity.
Physical activity done (Figure 5.7) showed a significant difference between the times of day
(F3.2, 54.7 = 8.3, P< 0.0005), this increasing throughout the day from the morning to the
evening, with low values in the morning and a higher plateau for the rest of the day. There
were no significant differences between control and fasting days (FI, 2 = 2.01, P = 0.17) nor
any significant interaction (F3.3, 56.6 = 1.5, P = 0.22).
-Control o Fasting
o 09:00h 12:00h 15:00h 18:00h 24:00h
Time of Day
Figure 5.7. Effect oftime of day upon physical activity score on control and fasting days. Mean + SE.
5.3.1.4. Mental activity
With mental activity also (Figure 5.8), there was a significant difference with time of day
(F2.9, 50.9 = 12.9, P< 0.0005), with low values in the morning and a higher plateau for the rest
of the day. There was no significant difference between control and fasting days (FI, 17 = 2.8,
P = 0.12) and no significant interaction between the two factors (F2.8, 46.8 = 0.99, P = 0.40).
88
~ -Control o Fasting Q 3 CJ
00
~ 2 .... > .... .... CJ
-< 1 -= .... = ~ 0 ~
09:00h 12:00h 15:00h 18:00h 24:00h
Time of Day
Figure 5.8. Effect of time of day upon mental activity score on control and fasting days. Mean + SE.
5.3.1.5. Social activity
Social activity done (Figure 5.9) showed a significant difference between time of day and of
social activity (F2.4, 40.2 = 14.7, P< 0.0005), increasing in the same way as physical activity.
Again, there was no significant difference between control and fasting days (FI, 17= 0.07, P =
0.79) and no significant interaction (F 3.1,53.0 = 0.54, P = 0.66).
~ 4 -Control o Fasting Q CJ
00 3 ~ .... > 2 '..C CJ
-< 1 -= .... CJ
0 Q 00
09:00h 12:00h 15:00h 18:00h 24:00h
Time of Day
Figure 5.9. Effect of time of day upon social activity score on control and fasting days. Mean +SE.
89
5.3.1.6. Fatigue
Fatigue (Figure 5.10) showed no significant difference between control and fasting days (F I.
17 = 2.1, P = 0.16). However, there was a significant difference between the times of day (F2.8.
47.6 = 4.8, P = 0.006) with fatigue falling during the morning and then rising throughout the
afternoon and later into the evening. Fatigue was significantly lower on retiring. There was
no significant interaction between the factors Day x Time of day (F2.6. 44.9 = 1.10, P = OJ
-Control o Fastin2
3 e Q u 2 rJ'1 ~ = ~ 1 ... ... ~ ~
0
09:00h 12:00h 15:00h 18:00h 24:00h
Time of Day
Figure 5.10. Effect of time of day upon fatigue on control and fasting days. Mean + SE.
5.3.1.7. Amount of physical activity wished for
The amount of physical activity that subjects wanted to perform showed a significant
difference between control and fasting days (Fl. 17 = 5.5, P = 0.031), lower values being
associated with the fasting days (Figure 5.11). There was also a significant effect of Time of
day (F3.1, 51.8 = 5.1, P = 0.004), values being highest around noon and the early afternoon and
then declining after this time. There was no significant interaction (F3.1. 53.0 = 0.76, P = 0.52).
90
• Control o Fasting e 3 0
~ rI'l
-= 2 fI.l
~ - 1 = ~ .,. fI.l ~ 0 -= ~ 09:00h 12:00h 15:00h 18:00h 24:00h
Time of Day
Fig~re 5.11. Effect of time of day upon the desire to perform physical work on control and fastmg days. Mean + SE.
5.3.1.8. Amount of mental activity Wished for
Subjects wanted to do less on fasting than control days (F I, 17 = 2.1, P = 0.017), Figure 5.12.
There was also a significant difference between the times of day (F2.8. 47.2 = 7.5, P<0.0005),
the profile being very similar to that of the desire to perform physical activity (Figure 5.11).
There was no significant interaction (F3.5, 58.9 = 1.8, P = 0.15) .
• Control o Fastin2 e 3 0 ~
rI1
-= 2 fI.l
~ - 1 = ..... = ~
~ 0 -1
09:00h 12:00h 15:00h 18:00h 24:00h
Time of Day
Fig?re 5. 12. Effect of time of day upon the desire to perform mental activity on control and fastmg days. Mean +SE.
91
5.3.2. Urine osmolality
Figure 5.13 shows mean urine osmolalities during the course of the control and fasting days.
There were significant effects of Day (FI, 17 = 30.7, P<0.0005), Time of day (F23, 39.8 = 5.6, P
= 0.005) and a significant interaction between the Day x Time of day (F2.5, 41.7 = 15.4,
P<0.0005). The results show that the urine was fairly concentrated after waking from the
night's sleep. Urine osmolality then fell during the daytime on the control days, when
daytime fluid intake was allowed, but tended to increase further during the daytime on the
fasting day.
C 1000 -Control o Fasting •• - 800 ~--Q~ e · 600 ~ e o ~ 400 ~ e =--•• 200 ... ~
0
09:00h 12:00h 15:00h 18:00h
Time of Day
Figure 5.13. Mean +SE of Urine Osmolality under Non-Fasting and fasting conditions.
5.3.3 Physical and mental performance
5.3.3.1. Hand grip strength
For grip strength of the dominant hand, there were a no significant effects of Day (F 1,7 = 1.5,
P = 0.23), Time of day (F2.6, 44.4 == 1.7, P = 0.19) or interaction between Time x Day (F2.4, 41.4 ==
1.4, P == 0.27) (Figure 5.14).
92
Q. •• J.. 50 - -Control o Fasting
~ '"0
= = 45 = e = e •• 40 ~
= ~ 09:00h 12:00h 15:00h 18:00h
Time of Day
Figure 5.14. Maximum hand grip strength (dominant hand). Mean + SE.
5.3.3.2. Stroop test
For the Stroop test, there was a no significant difference for Day (FI, 17 = 2.5, P = 0.13) but
there Was a highly significant effect of Time of day (F2.o, 33.7 = 10.8, P<0.0005), with
performance improving (time taken decreasing) as the day progressed (Figure 5.15). There
was no significant interaction between Time x Day (F2.4, 41.2 = 0.54, P = 0.62)
14 -Control o Fastin2 0 .....
..... fI}
=~ 13 ~ ~ ~
12 = ..... ..... ~ -~ Q.
.9 e 11 ~ 8
10
09:00h 12:00h 15:00h 18:00h
Time of Day
Figure 5.15. Time taken to complete test. Mean + SE.
93
5.3.3.3. Jump height
Figure 5.16 shows the results for jump height. There was no significant effect of Day (F 1,17 =
1.4, P = 0.26) but a significant effect of Time of day (F2.5, 43.2 = 11.2, P<0.0005), performance
improving throughout the daytime and evening. There was a significant interaction between
the two factors (F2.4, 40.1 = 4.9, P = 0.009), the improvement during the daytime being less
marked on the fasting day, particularly in the late afternoon.
-Control o Fasting -. 60 e ~
--- 50 .... -= ~ 40 .... ~
== c.. 30 e = 20 ~
09:00h 12:00h 15:00h 18:00h
Time of Day
Figure 5.16. Maximum height jumped. Mean + SE.
5.3.3.4. Throwing darts
Total Score for darts 4-17 (see Figure 5.17) showed no significant effect of Day (Fl. 17 = 0.72,
P == 0.41). There was also no significant time-of-day effect (F2.5.41.9= 0.93, P = 0.42) but an
interaction that was marginally significant (F2.6, 44.8 == 2.3, P = 0.096), because the scores fell
towards the end of the day during fasting only.
94
The number of misses ("zero" scores) was also analysed (Figure 5.18). Here also, there was
no significant difference between Day (F 1, 17 = 0.06, P = 0.81) or Time of day (F2.2. 37.4 = 1.6,
P == 0.21). There was also no significant interaction (F2.2.38.2 = 1.12, P = 0.36).
- -Control o Fasting = 60 .... ~ ~ Q 50 ~
rI'l ~
1: = 40 ~
09:00h 12:00h 15:00h 18:00h
Time of Day
Figure 5.17. Total scores for darts 4-17. Mean + SE. For calculation of Score, see text.
~ -Control o Fasting e 6
~
N a- S ~ ~
S = 4 Z ~
3 a-~
~ 09:00h 12:00h 15:00h 18:00h
Time of Day
F' Igure 5.1S. Mean number of zeros scored. Mean + SE
95
As with the other estimates of performance at the task of throwing darts, Mean score per hit
(see Figure 5.19) showed no significant effect of Day (F),17 = 1.9, P = 0.19), Time of day
(F2.5,42.3 = 0.58, P = 0.60) or interaction between the two factors (F2.6,44.9 = 1.7, P = 0.20).
5.5 -Control o Fasting .... ••
== 5.0 .........
~ Q 4.5 CJ
rJ'l
4.0 -I
09:00h 12:00h 15:00h 18:00h
Time of Day
Figure 5.19. Mean score per hit. Mean + SE. For calculation of Score/Hit, see text.
96
5.3.4. Correlations between the variables.
To calculate these, the three scores for physical, mental and social activities actually
performed were combined (ScoreP), as were the two scores for the wished-for amounts of
physical and mental activity (ScoreW). In the correlations, all pairs of values from the four
times of day and both control and fasting days were used. That is, each subject gave 8 pairs of
values (09:00, 12:00, 15:00 and 18:00 h for both control and fasting days). The correlation
matrix is shown in Table 5.1. As this Table indicates, the significant correlations were:
ScoreP vs. Fatigue=-0.16; ScoreP vs. ScoreW=+0.39; ScoreP vs. Stroop test=-0.20.
Fatigue vs. ScoreW=-0.62
ScoreW vs. Urine=-0.18
Darts total score vs. Darts number ofzeros=-0.74
Stroop test vs. Grip strength=-0.24; Stroop test vs. Jump height=-0.32
It will be noted that there were no significant correlations between performance at darts and
the other variables.
97
Table. 5.1. Correlations between the variables using the method of Bland and Altman (1995). Significant (P<0.05) values given numerically. Values in brackets indicate direction of correlation when marginally significant (0.10 > P > 0.05). Blanks indicate correlations non-significant (P>0.10).
Variables ScoreP Fatigue ScoreW Urine DartsTotal Darts Zeros Stroop Grip strength Jump height
ScoreP X -0.16 0.39 (-) -0.20 (+) (+)
Fatigue X X -0.62 (+) (-) (-) (-)
ScoreW X X X -0.18 (+) (-) (-) (+) (+)
Urine X X X X (-) (+) (-) (-)
DartsTotal X X X X X -0.74 (-) (+) (-)
Darts Zeros X X X X X X (+)
Stroop X X X X X X X -0.24 -0.32
Grip strength X X X X X X X X (+)
Jump height X X X X X X -0.32 I
X X - I -- --- -
98
5.4. Discussion
Many of the results confirm those obtained in the field study and pilot study; that is, there
was clear evidence for changes during fasting to: drinking and eating habits, amounts of
wished-for physical and mental activity, and hydration status of the body. By contrast, the
changes observed in grip strength, performance at the Stroop test and jump test, and the
ability to throw darts accurately was far less marked.
There was limited evidence to support the view that subjects made preparations before the
time of fasting. More of them drank and ate before sunrise on the fasting than on the control
day (Figures 5.1 and 5.4). The most common reason cited for drinking or eating was
"Thirsty" or "Hungry" but "Prepare" was cited almost as frequently before the day of fasting
(Figures 5.2 and 5.5), although the increases were not significant statistically. After sunset, all
subjects ate and drank. Again, thirst and hunger were cited most frequently but "Recover"
was cited significantly more frequently after the day of fasting and almost as frequently as
thirst or hunger (Figures 5.3 and 5.6).
These preparations for fasting and recovery from it afterwards agree with the work previously
found by us in subjects during Ramadan (Hakkou et al., 1994; Waterhouse et at., 2008a,
2008b, 2009 and also in Chapter 3). Whilst it can be argued that such preparations are
intuitively likely, it must also be remembered that the fast lasted for one day only (unlike the
case in Ramadan) and the subjects had no prior knowledge of the demands of Ramadan, none
of them being Muslim. That is, as argued previously (Waterhouse et al., 2008b), the link
between fluid and food intakes and the amount of drink or food ingested tends to break down
in these circumstances. In this respect, there is some similarity with intakes when the meal
99
serves an important social function, when intakes might be greater than required (de Castro,
1987; Waterhouse et al., 2005).
The subjects showed decreases in the types of activity in the daytime during fasting (Figures
5.7-5.9), though the differences were not statistically significant. Similar profiles were seen
for the amounts of physical and mental activity that subjects wished to undertake (Figures
5.11, 5.12) but in these cases the differences were statistically significant. During the
daytime, fatigue tended to be higher on the fasting day (Figure 5.10), even though not
significantly so. These results lend limited support to those found by us previously
(Waterhouse et aI., 2008b), indicating that subjects "spare" themselves when fasting; they
support the view that fasting in Ramadan has negative effects upon fatigue (in part due to a
fall of glucose intake) and performance in general (see, for example, Kadri el aI., 2000;
Karaagaoglu and Yucecan, 2002; Leiper et aI., 2003; Roky el aI., 1999,2000).
In the evening, the amounts of activity actually performed and wished-for activity tended to
increase towards, or even beyond, values on control days, but these increases were not as
marked as found previously (Waterhouse el al. , 2008a,2008b), the interaction terms not
being statistically significant. This lack of increase after the end of the fast is likely to reflect
the social role played by food intake (de Castro, 1987, 1997, 2000), a role that is more
marked in the Muslim community during Ramadan than in non-Muslim students performing
a single day of fasting.
Urine osmolality was quite high on waking on both days (Figure 5.13), indicating the
development of dehydration during sleep. The subsequent fall during the daytime on control
100
days is due to the intake of fluids during the daytime. By contrast, osmolality (and
dehydration) continued to rise during the daytime on the fasting day, as would be expected.
Such results have been found previously in Ramadan (Reilly and Waterhouse, 2007) and also
agree with those found in the field study (Chapter 3, Waterhouse et aI., 2009) and the pilot
laboratory-based study (Chapter 4). The observation that urine osmolality was not lower at
09:00h on the fasting day indicates that fluid intake before the start of the fasting period did
not correct overnight dehydration. That is, even though subjects were more likely to drink
before the start of the fasting period (see Figure 5.1), the amount of fluid they drank was
insufficient. This lack of preparation for the demands of daytime fasting can be contrasted
with the extra fluid intake observed in Ramadan in the field study (Chapter 3).
The lack of changes observed with grip strength (Figure 5.14) agrees with the findings from
the pilot study (Chapter 4). In addition, no circadian rhythm was demonstrated on either day
as well as no significant difference between the fasting and control days. It must be
concluded either that this aspect of physical performance (maximal contraction of a limited
muscle group) does not change with the amount of fasting undertaken in this study or that, as
performed by these subjects, the test was not sufficiently sensitive. Since other studies have
shown a circadian rhythm of grip strength (Reilly et aI., 1997), the latter reason (lack of
sensitivity as performed in the current study) seems more likely.
Unlike grip strength, jump height rose significantly as the day progressed (Figure 5.16). In
addition, the two days differed, with the rise on the fasting day being less marked. This
difference was most marked at 18:00 h when the effects of fluid restriction are likely to have
been most marked. Research involving vertical jumps in conditions of fluid and food
101
restriction is sparse. However, Judelson et al. (2007) investigated the effect of hydration state
on this measure and found no significant differences in vertical jump height in euhydration
and hypohydration at 2.5% and 5% body mass reductions. This result differs from the present
one. Possibly, it is because Judelson et al. achieved these levels not only by prohibiting
water fluid intake but also requiring the subjects to perform an exercise-induced heat stress
trial on the previous day. Nevertheless, the present finding has implications for those required
to perform physically demanding tasks after an interval of fasting.
Considering physical performance in general, it has often been considered that muscle power
is comparatively immune to effects of sleep loss and fasting (Reilly et al., 1997). However,
motivation to perform activities and neural control of movement are both affected negatively
by sleep loss and fasting (Reilly and Waterhouse, 2009), and these factors might have
contributed to the decline in jump height observed later in the day when fasting. Whatever the
detailed explanation, the present findings reinforce the implications (see above) for those
required to perform physically demanding tasks after an interval of fasting.
The Stroop test showed a clear circadian rhythm (Figure 5.15) with performance improving
(time taken to finish the test decreasing) until about 15:00 h. These accords with other tests of
mental performance which tend to peak slightly earlier than core temperature (Folkard,
1990). The reason generally given to explain the earlier peak than for core temperature is that
mental performance is negatively affected by increasing time awake far more than is core
temperature (Adam et al. , 2008); as a result, performance begins to fall any time from noon
onwards as fatigue due to time awake increases. Mental performance is also adversely
affected by sleep loss (Akerstedt et al., 2007) and by fasting (Adam et aI., 2008). In the
102
current study, performance was lower on the fasting day (Figure 5.15) but not by amounts
that were statistically significant. This lack of statistical significance might reflect sample
slze.
With regard to throwing darts, no statistically significant rhythms were found in the any of
the three methods used for scoring this task (total score, number of misses and score per hit,
Figures 5.17-5.19, respectively). This contrasts with previous work (Edwards et al., 2007a)
where rhythms peaking in the afternoon have been found. Also, there were no statistically
significant effects of fasting. Nevertheless, inspection of the Figures suggests that
perfonnance tended to improve during the course of the daytime on control days (total score,
Figure 5.17 and scoreihit, Figure 5.19) whereas, though rising in the first part of the fasting
day (09:00 h and 12:00 h), it then deteriorated at 15:00 h and 18:00 h. This deterioration in
comparison with the control day is shown by the falls in total score (Figure 5.17) and score
per hit (Figure 5.19), and by the increased number of misses (Figure 5.18). Such differences
are unlikely to be due to effects of time awake, which were almost identical on control and
fasting days. Instead, the deterioration at the end of the daytime is more likely to reflect
negative effects of fasting (Reilly and Waterhouse, 2007) and to bring the findings in
agreement with those found in the jump test and discussed above. The high variability in the
results (resulting in the lack of statistical significance) might have arisen in part from a
learning effect, subjects differing in previous experience of throwing darts.
Whilst it is not possible to deduce causal links from correlations, the results from such
analyses can be used to support or refute possible links that have been deduced from other
studies of interactions between circadian rhythms, effects of sleep loss and restricted food and
fluid intakes. For example, the following possible scenarios can be devised by considering
103
the results in Table 5.1: if individuals are tired (Fatigue), they tend to perform less physical,
mental and social activities (ScoreP) and wish to do less (ScoreW); and, if they are
dehydrated (Urine osmolality), then one of the general effects of this is to feel less inclined to
perform physical or mental tasks (Score W). There might also be correlations between
different performance tasks, these both being affected by the same demands of a day of
fasting. For example: the less activities that have been undertaken (ScoreP), the poorer will
performance be at some tests (Stroop test); and poorer performance at one task (Stroop test)
is likely to be associated with poorer performance at other tasks (Grip strength and Jump
height). Clearly, much further work is required to assess these suggestions.
5.4.1. General conclusions
5.4.1.1. Effects of fasting
The present results accord with the concept that fasting is associated with a general decline in
performance and the sense of well-being, a conclusion that has been drawn in previous
studies (Waterhouse et al., 2008a, 2008b), the current studies (Chapters 3 and 4 and
Waterhouse et ai., 2009) and reviews of the field (Reilly and Waterhouse, 2007). Many of the
correlations (Table 5.1) suggest that there are general deteriorations in several aspects of
performance, a consideration of the correlations that were only marginally significant
(O.IO>P>O.05) adding some further support to the view that there exist many negative effects
during food and fluid restriction. There are important implications of these findings for those
who are fasting, particularly in Ramadan, and these will be considered in Chapter 7.
104
5.4.1.2. Relationship between field and laboratory-based studies
Considered as a whole, these results have several important implications for attempts to study
some of the effects of Ramadan fasting in the laboratory. It can be concluded, first, that a
laboratory-based study lasting only one day gives results that are comparable to those in
Ramadan (when at least 28 successive days of fasting are involved); second, non-Muslim
subjects often behave like Muslims with regard to preparations for fasting and recovery from
fasting. When differences between field- and laboratory-based studies exist, particularly in
the evening, it seems to be at least partly due to the lack of a communal social element,
something that is strong amongst Muslims in Ramadan.
In conclusion, a protocol which uses a single day of fasting in the laboratory environment is a
useful tool for investigating the kind of problems that will arise in Ramadan. Also, subjects
can be non-Muslim (and so have no first-hand experience of fasting in Ramadan). The
advantages of such a protocol are that the choice of subjects is far less limited and also that
more detailed tests can be perfonned in the laboratory than is possible in the field.
5.4.1.3. Measurement tools
However, some results were not as predicted, particularly those for gnp strength (no
circadian rhythm nor effect of fasting) and throwing darts, where there were marginal effects
of fasting but no circadian rhythm). The lacks of effect of fasting might indicate that the
attributes required for such tests were not affected adversely by the amounts of food and fluid
restriction that were used. However, this is slightly surprising since many aspects of athletic
performance have been found to be worse in Ramadan (Reilly and Waterhouse, 2007). Of
more concern, however, is the failure to demonstrate circadian rhythmicity in these variables,
105
since such rhythms have been found in previous studies (Reilly et aI., 1997; Edwards et al..
2007). The explanation for this is not certain but it suggests that the variability associated
with the tasks was higher than that normally found. Lack of training in the tasks before the
experimental trials and/or insufficient supervision are two possible explanations, but these
suggestions are speculative.
5.4.1.4. Problems in these types of study
There is another problem that is common to all the studies (both field- and laboratory-based)
that have been described so far. It results from the subjects being free to choose many aspects
of their lifestyle, including whether or not to drink before sunrise and after sunset and, if
drink or food was taken, its type and amount. For example, some subjects drank on both
occasions, some on neither and some on only one occasion. Such differences increase the
amount of "noise" in the data and also limit some of the statistical analyses that can be
performed. Other differences exist; for example, the amount of physical or mental activity
actually performed will not have reflected the individuals' desire to perform physical or
mental tasks but rather their commitments, whether these are to work, study or child-rearing.
This difference between what was done and what would have been preferred to have been
done is clear by comparing the results of Figures 5.7-5.9 (actual performance) with those of
Figures 5.11 and 5.12 (wished-for activity). Such differences are part of normal living, of
COurse - the "real world" - but they complicate analysis of the results as well as having
important practical implications for those fasting.
106
One improvement would be to allow subjects to behave as they wished (subject to the
constraints of the protocol) but to ensure that they behaved in the same way for both the
control and fasting days. In addition, more control of the hours before the start of the protocol
(the food eaten the night before and the amount of sleep, for example) would be
advantageous due to its reducing these further sources of variation. If subjects adhered to
such a Protocol, this would form the background to interventions in which the length of time
spent fasting could be controlled. Such an intervention study would enable a clearer
assessment of the effects of fasting to be obtained. In practice, adhering to all these
requirements is difficult for subjects living normally. However, at least some of the
requirements can be met more easily and such a study is described in Chapter 6.
107
Chapter 6
An Intervention Study with Controlled
Time for Sleep and Variable Length of
Fasting
\~~
~t~ JMU
Liverpool John Moores University
6.1. Introduction
The results from previous field studies (Waterhouse et at. , 2008a,2008b) and from the field
study (Chapter 3) and two laboratory-based studies (Chapters 4 and 5) discussed so far in this
thesis have enabled a clearer picture of effects arising from the demands of fasting during the
course of a day in Ramadan to be obtained. However, the studies are restricted in that they
are descriptive only. Moreover, subjects have been free to choose their activities, times of
sleep and naps and, apart from when fasting, the timing and type of food and fluid taken in.
Whilst this reflects the position in Ramadan, it produces interpretive difficulties. Thus, it
cannot be deduced if a measured change in a variable (mental or physical performance, for
example) is due to lack of food and fluid intake and/or changed fatigue due to altered sleep
times. As indicated in the literature review, any of these factors could lead to the observed
results.
The present study, an intervention study, has been planned to deal with this limitation. A
variety of variables will be measured at three times of day after subjects have undergone
different lengths of prior fasting. By contrast, food intake during the evening before the test
day (supper) and the length of sleep will be unchanged. The intervention will be in three
parts, the lengths of fasting being 4 h, 8 h and 16 h, these being administered in random order
for the group as a whole.
With such a protocol, any changes in the measured varIables with length of fasting cannot
result from any change in sleep; rather, they must reflect the duration of prior fasting. The
analysis of the results will focus upon the effects of speCific'du~atio~:s of fasting upon these
variables. It is hypothesised that general performance will deteriorate with fasting, the
109
amount of deterioration being in proportion to its duration. Because there is no change in the
amount of prior sleep, sleep loss (found in the other studies and complicating interpretation of
the results) cannot be a possible cause in the current study.
6.2. Methods
6.2.1. Subjects
Twelve subjects (8 males and 4 females, mean age 34.4 (SO=3.2) years, height 1.74
(SD==0.09) m took part in the study. Subjects were recruited from the student population at
Liverpool John Moores University by word-of-mouth. Subjects volunteered to participate in
the study with the understanding that participation was not monetarily compensated and they
could withdraw at any time without giving any reason and with no negative consequences.
6.6.2. Protocol
For the two days before each of the three parts, the subjects' normal sleep times were
observed and their eating habits were normal (breakfast, lunch and evening meal), with a
small supper before retiring. Performance and other variables (see below) were assessed at
08:00, 12:00 and 16:00 h. The intervention, which was designed to change the length of
fasting before the measurements made at 16:00 h, consisted of three parts, the order of them
being randomised for the group as a whole. The three parts were:
A. Supper before retiring but no breakfast and no lunch, and no fluid intake apart from a glass
of water at 08:00 h - a fasting period, by 16:00 h, of 16 hours. This is called the Fasting
condition.
110
B. Supper before retiring and a standard breakfast (at 08:00 h) including a glass of water, but
no lunch or other fluid intake - a fasting period, by 16:00 h, of 8 hours. This is called the
Breakfast condition.
C. Supper before retiring, breakfast (at 08:00 h) including a glass of water, and lunch (at
12:00 h) - a fasting period, by 16:00 h, of 4 hours. This is called the Control condition.
6.2.3. Measurements and apparatus
On the three days of the experiment, subjects came to the laboratory for testing at 08 :00,
12:00 and 16:00 h. On each occasion, many of the same variables as used in Chapter 5 (the
second laboratory-based study) were measured but further variables were added to increase
the range of the investigation and its value to studies of Ramadan.
6.2.3.1. Actimetry
This was measured from 20:00 h on the day before each experimental day. This is a non
invasive and objective measure of physical activity; it has been widely used to investigate
amounts of physical activity, and to compare waking activity with sleeping inactivity
(Carvalho-Bos et al., 2003). The apparatus (Actiwatch AW4 Software England) was worn on
the non-dominant wrist from just before suppertime on the day before the experiment until
17:00 h at the end of the experiment. It was set to record activity at I-min intervals. The
activity record was down-loaded onto a laptop computer for later analysis each time the
subject Came to the laboratory.
The other variables measured, and the order in which they were given, were:
III
6.2.3.2. Questionnaires.
These were modified versions of those used previously (Waterhouse et al., 2008) and
assessed food and fluid intakes, sleep, and subjective estimates of mood, mental performance
and physical performance.
6.2.3.3. Body mass and urine osmolality.
In addition to body mass (Seca 702, Seca GmbH & Co.KG, Hamburg, Germany), the indirect
measure of water content, urine osmolality (Osmocheck Pocket Pal OSMO, Vitech Scientific
Ltd, Japan) was measured.
6.2.3.4. Performance measures - throwing darts.
This is a measure of hand-eye co-ordination (see Edwards et al., 2007, 2009). The subjects
threw darts at a circular target (20 cm diameter) placed on the wall at a distance of 2.37
metres; the target consisted of 10 concentric rings of diameter 2 cm, 4 cm, 6 cm, ...... 20 cm.
Participants were instructed to stand 2.37m away from the target (see Appendix 5.1) and to
throw one dart (Unicorn Precision darts, 24 g, Unicorn Products Ltd, England) a total of 20
times at the target. After each throw, the score for each dart was measured (according to
which of the rings the dart was in) and then the dart was collected for the next throw. When a
dart missed the target, the score was recorded as zero (a "miss"), regardless of the size of the
miss (see Appendix 5.1).
112
6.2.3.5. Exercise.
This was on a cycle ergometer (Ergo Bike Premium 8i from Germany's Doum Dedronic).
The trial started at 120 watts and then increased by 10 watts per minute to a final value of 160
watts which was maintained for the last minute, the trial taking 5 min to complete. The rate of
pedalling was chosen by the SUbjects.
Before and immediately after the bout of exercise, the respiratory exchange ratio (RER),
blood lactate and heart rate were measured. For the measurement of RER, Douglas bags and
standard equipment for measuring gas volume and oxygen and carbon dioxide concentrations
(Servomax Gas Analyser, Cranlea and company, Birmingham) were used (see Appendix 6.1).
Blood lactate was taken from a finger-prick sample and analysed by a Lactate Pro Test Meter
(Model LT701O, Arfray Inc, Kyoto Japan). Standard healthcare precautions were taken for
blood sampling and analysis (See Appendix 6.2). Heart rate was measured using a monitor
(Polar, Kempele, Finland) strapped to the chest and a data logger attached to the subject's
wrist.
Immediately after exercise, subjects were asked to assess their perceived exertion after
exercise using the Borg scale (Borg, 1998) - see Appendix 6.3.
6.2.4. Treatment of results
6.2.4.1. Questionnaires
The results were treated as described in Chapter 3.
113
6.2.4.2. Actimetry
The actimetry record was divided into three sections: the middle three hours of sleep
(assessed from the activity record which clearly indicated times of retiring and rising), a two
hour "morning" section (09:00 h to 11 :00 h) and a two-hour "afternoon" session (13 :00 h to
15:00 h). For each of these, the summed activity count was used.
6.2.4.3. Darts
The first and last three throws were excluded, to allow for any effects due to "getting going"
and being "nearly finished" (Edwards et aI., 2007). The participants were not aware that the
results from some of the throws would not be analysed. The central 14 scores were used to
assess accuracy in two ways: the total score and the number of errors (zero scores). For more
details, see Appendix 5.1.
6.2.5. Statistics
Unless stated otherwise, the data were analysed by the means of the Statistical Package for
Social Science (SPSS) for Windows, version 17, using a two way Analysis of Variance
(ANOV A) with repeated measures model. The main factors were Condition (3 levels:
Control, Fasting and Breakfast) and Time of Day (3 levels: 08:00, 12:00 and 16:00 h). To
correct for violations of sphericity, the degrees of freedom were corrected by using either
HUYnh-Feldt (>0.75) or Greenhouse-Geisser «0.75) in accordance with two way repeated
measures ANOV A assumptions (Field, 2000). Significance was set as P<0.05.
114
6.3. Results
6.3.1. Questionnaires
6.3.1.1. Sleep times and food and fluid intakes
The questionnaires were inspected to ensure that the subjects had adhered to the protocol with
regard to food and fluid intakes. Also, it was possible to assess that each subject's time in bed
was similar on the three occasions (less than 30 min differences for any subject), and that no
daytime naps were taken during the experimental days.
By comparing the fluid and food intakes during supper the day before each experiment, it was
also possible to assess the types of fluid drunk (Figure 6.1). Water was almost universally
drunk, tea or coffee were drunk about 0.6 of possible occasions and fruit juice on about 0.4 of
possible occasions. These differences in frequency of intake between types of drink were
significant (P=O.Ol, Cochran) but the frequencies did not differ significantly between the
three parts of the experiment (P=0.5l, Cochran), again indicating that subjects adhered to the
requirements of the protocol.
6.3.1.2. Activities performed
There Was a significant difference between Control, Breakfast only and Fasting days in the
amount of physical activity performed (F 1.7, 19.2 = 9.46, P = 0.002), this decreasing when
fasting (Figure 6.2A). There was also a highly significant effect of Time of day (FI.9, 21.3 =
18.4, P<0.0005), activity being least at 08:00 h. There was no significant interaction between
Day x Time of day (F2.9,32.3 = 0.17, P = 0.91).
115
1.20 - Control [] Breakfast o Fastin!! 'IJ = 1.00 0 .. 'IJ ~ 0.80 u u 0 0.60 c.., 0 0.40 = 0
0.20 .. ..... u ~ 0.00 I. ~
Water Tea/Coffee Fruit Juice
Type of Drink
Figure 6.1. Fraction ofpossible occasions that different types oftluid wer drunk during supp~r just before the Control, Breakfast and Fasting days. For calculation of ' Fraction of Possible Occasions", see Chapter 5.
Mental activity also showed a significant effect of Day (F 1.5 , 16.3 = 5.65, P = 0.020), being
marginally less than on control days when no breakfast and/or lunch was eat n (Figure 6.28).
There was a significant effect of Time of day (F 1.8, 19.4 = 20.16, P<0.0005) values at 08:00 h
being lower than at the other two times of measurement. There was no significant interaction
between the two factors (F28, 30.9 = 0.14, P=0.93),
Social activity showed a significant difference between the three types of day (FJ.7, 18.8 = 4.78,
P = 0.025) with values on the control day being greater than when fasting (Figure 6.2 ).
There was a significant difference between times of day (FJ.7, 19.0 = 5.26 P = 0.018) activity
at 08:00 h being less than at the other two times of day. There was no significant interaction
between the factors (F2.8, 30.6 = 0.23, P = 0.87).
116
A
3
~ J. 0 u 2 00
1
B
3.0
~ 2.5 J. 0 U
00 2.0
1.5
c 3.0
~ 2.5 t.. o U
00 2.0
1.5
-Control CBreakfast o Fasting
08:00h 12:00h 16:00h
Time of Day
-Control CBreakfast o Fastin!!
08:00h 12:00h 16:00h
Time of Day
-Control ClBreakfast o Fasting
08:00h 12:00h 16:00h
Time of Day
Figure 6.2. Scores for (A) physical activity, (B) mental activity and ( ) social activity during Control, Breakfast and Fasting days. Mean + SE.
117
6.3.1.3. Activities wished for
The amount of physical activity wish for (Figure 6.3) showed a marginal effect of Day ( 1.5,
16.9= 3.52, P = 0.063), with a trend for the control day to be greater than th day f fa ting.
There was a significant effect of Time of day (FI.2, 13.2 = 7.48, P = 0.014), values d creasing
with the amount of time spent fast ing. There was no significant interaction between the two
factors (F2.7, 29.8 = 0.08, P =0.96).
~ 3.0 Q ~
rJ1 2.5 ..c rI)
~ 2.0 -~ 1.5 .-rI) £ 1.0 ~
-Control
08:00h
[J Breakfast o Fasting
12:00h 16:00h
Time of Day
Figure 6.3. The effects of time of day and condition (Control, Breakfast and Fasting) Upon physical activity wished for. Mean + SE.
For mental activity wished for (Figure 6.4), there was a significant effect of day (FI.8, 19.5 =
12.29, P =: 0.001), control values being highest. Also, there was a signi {jcant ffect of Time
of day (FI.9, 20.7 = 24.04, P<0.0005), values at 08:00 h being lower than at the other two times.
There was no significant interaction between the condition and th time of day (F3.0, 330 =
0.10, p= 0.96).
118
-Control
08:00h
CBreakfast
12:00h Time of Day
o Fasting
16:00h
Figure 6.4. The effect of time of day and condition ( ontral Breakfa t nlyand Fa ting) upon mental activity wished for. Mean + SE.
6.3.1.4. Perceived sleepiness
For perceived sleepiness (Figure 6.5), there was no ignificant differ nce between th thrc
types of day (F1.5, 16.4 = 2.53 , P = 0.12). However, there was a significant effect f Time of
day (FI.8, 19.9 = 5.86, P = 0.012) with sleepiness at 16:00 h being significantly lower than at
08:00 h. There was no significant interaction between Day x Time of day (Fa . 0.6 = 0.2 1, P
0.88).
3.0
fIJ 2.5 fIJ ~ c 2.0 •• ~ ~ ~ 1.5 -r'-1
1.0
-Control CBreakfast o Fastine
08:00h 12:00h 16:00h
Time of Day
Figure 6.5. The effects of time of day and condition upon perceived sJeepi nes . Mean + S
119
6.3.2. Urine osmolality
There were significant effects of Day (F 1.9, 20.8 = 28.3, P<O.OOOS), Time of day (F 1.2, 13.5 =
10.4, P<O.OOS) and a significant interaction between the Day x Time of day (F2.8 , 30.9 = 28. t,
P<O.OOS) (Figure 6.6). The significant interaction arose because, whereas urine osmolality
was similar on all days at 08:00 h and fell to lower values on contro l days (due to fluid
intake), it rose on the other days when fluid intake was prohibited (after 12:00 h on the day
when only breakfast was taken and after 08:00 hand 12:00 h on the day of fasting).
1200 • Control C Breakfast 0 Fastine:
400
08:00h 12:00h 16:00h
Time of Day
Figure 6.6. Urine osmolality during the daytime in the three experimental condition . Mean + SE. .
6.3.3. Actimetry
Figure 6.7 shows the summed activity scores at the three times of day. There was no
significant effect of day (FI! , 11.7 = 1.S8, P = 0.24) but a highly significant effect of Time of
day (F1.3, 14.7 = 14.87, P = 0.001), due to the low values during sleep. There was no significant
interaction between Day x Time of day (F2.2, 24 .3 = 1.08, P = 0.36), indicating that objective
measures f " o activity showed no differences between the three experimental days.
120
16000 .... = :::s 12000 o U ~ .... > .... .... Cj
-<
8000
4000
• Steen CMorninf! o Afternoon
Control Breakfast Fasting
Time of Day
Figure 6.7. Effects of time of day and conditions upon summed activities. Mean + . For definitions of Sleep, Moming and Aftemoon periods, see text.
6.3.4. Objective measures of performance - throwing dart
Total Scores for darts (Figure 6.8) showed no significant effect of Day (FI.8,19.3=0.05 ;
P=O.93), no significant effect of Time of day (FI.7,19.1 = 1.1 2, P = 0.35) and no ignificant
interaction between Day x Time of day (F2.9,32.4 = 1.24, P = 0.34).
The number of misses, or 'zero' scores (Figure 6.9), al so showed no significant effects of
Day (FI.9. 21.6= 1.07; P=0.34), Time of day (FI.8. 19.9 = 0.65 , P = 0.52) or interaction (F2.8 .
30.4=1.70, P = 0.19).
121
• Control CBreakfast o Fastini!
08:00h 12:00h 16:00h
Time of Day
Figure 6.S. Total scores for darts 4-17 on control, breakfast only and fasting day at th 3 times of measurement. Mean + SE .
rIJ
e ~ 1.4 N 1.2 -~ 1.0 .Q e 0.8 = 0.6 Z 0.4 rIJ
1:: 0.2 ~ 0.0
• Control C Breakfast 0 Fasting
08:00h 12:00h
Time of Day
F' Igure 6.9. Mean number of zeros scored. Mean + SE.
122
16:00h
6.3.5. Changes produced by exercise
6.3.5.1. Body mass.
Body mass decreased slightly after each bout of exercise (Figure 6.l 0). However, these fa ll s
were not significantly different between Day (F 1.1 , 12 .2 = 0.78, P = 0.41) or Time of Day (F 14,
IS.S == 0.21, P = 0.74), and there was no signjficant interaction between the two factor (F2.7. 30.2
== 0.57, P = 0.63).
• Control C Breakfast 0 Fasting 0.00
-0.05 -0.10 -0.15 -0.20 -0.25 -0.30 -0.35 -0.40
08:00h 12:00h 16:00h
Time of Day
Figure 6.10. Fall in body mass produced by exercise. Mean + S .
6.3.5.2. Respiratory exchange ratio (RER)
Figure 6.11 shows the increases in RER produced by exercise. The incr ase d pended
significantly upon Day (FI.3, 14.2 = 5.29, P = 0.030), and there was a marginal effect of Time
of day (F IA, 15 .2 = 2.85, P = 0.10), the rise being least at 16:00 h. During fasting, these effects
of time of day were far less marked, as a result of which there was a significant interaction
between Day x Time of day (F2.7, 29.6 = 3.49, P = 0.032).
123
0.4
~ 0.3
~ .S 0.2 ~ rI.l
~ 0.1
-Control
08:00h
CBreakfast o Fasting
12:00h 16:00h
Time of Day Figure 6.11. Changes in RER produced by exerci e. Mean + E.
6.3.5.3. Lactate
Blood lactate levels rose after exercise (Figure 6. 12). The rise was mo t mark d n th
control day (FI2, 13.7 = 11.] 1, P = 0.003) and was also greater as the day progre sed (FI.6. 18.0=
10.68, P = 0.001). This increased rise as the day progres ed wa Ie s marked as th am unt r
fasting increased, these changes accounting for the significant interaction b tween Day x
Time of day (F2.3 ,25.4 = 7.32, P = 0.002).
~ rI.l
~ 3.0
-Control
08:00h
CBreakfast
12:00h
Time of Day
o Fasting
16:00h
Figure 6.12. Lactate ri e following exercise at different times of day and during ontro1 , Breakfast only and Fasting days. Mean + E.
124
6.3.5.4. Heart rate
Heart rate increased markedly after exercise (Figure 6.13). This rise depended upon the Day
(FI.3, 14.1 = 46.48, P<0.0005) with the rise increasing progressively with the length of fa ting.
There was no significant effect of Time of day (F 1.8, 19 .3 = 2. ] 0, P = 0.15) and no s ignifi cant
interaction (F3. I , 34.4 = 2.17, P = 0.11).
QJ rIJ
95 -Control [] Breakfast
~ 75 ~--__ ~~ __
08:00h 12:00h
Time of Day
o Fasting
16:00h
Figure 6.13. Rise in HR produced by exercise at different time of day on ontr I Breakfa t only and Fasting days. Mean + SE.
125
6.3.5.5. Rating of perceived exertion (RPE)
Figure 6.14 shows the ratings of percei ved exertion after the bout of exercise. There wa a
significant effect of Day (F I.4 , 15.9= 46.6, P<0.0005), with p rceived exertion increasing as the
length of fasting increased. There was also a significant effect of Time of day (F 1.7, 18.9 =
50.87, P<0.0005), exertion being perceived as greater later in the day. There was no
significant interaction between Day x Time of day ( 2.4, 26.6 = 0.66 P = 0.55).
16 .Control CBreakfast o Fasting
14
12
10
08:00h 12:00h 16:00h
Time of Day
Figure 6.14. Rating of perceived exertion (RP ) after bout of exercise. Mean + ~
]26
6.4. Discussion and Conclusions
Inspection of the subjects' records indicates that the protocol was adhered to - that is, the
duration of fasting varied between the three parts of the experiment (4 h, 8 h or 16 h for the
control, breakfast only and fasting day, respectively) but the times of sleeping and the amount
of food eaten in the evening before were the same. In addition, the amount of fluid drunk in
the evening before the experimental days did not vary (Figure 6.1). As a result of the
constancy of these aspects of lifestyle, differences between the three parts of the experiment
can be attributed to the lack of food and fluid intakes during the daytime rather than to a lack
of sleep the previous night or altered eating habits during the previous evening. In support of
the view that sleep was unchanged, the amount of sleepiness (Figure 6.5) did not vary
significantly with the amount of fasting. The observation that sleepiness decreased
progressively from 08:00 h to 16:00 h is to be expected (Waterhouse ef aI., 2001) and
supports the view that subjects were responding normally to the demands of wake time. The
actimetry record also (Figure 6.7) supports the view that sleep was similar in the three parts
of the experiment.
Subjective estimates of the amounts of activity performed in the daytime, whether physical,
mental or social activity (Figure 6.2), indicate that less activity was performed when fasting,
a result in accord with that found previously (Waterhouse ef al., 2008a, 2008b and in
Chapters 3-5), Moreover, even though there were no statistically significant differences
between morning and afternoon activities produced by restrictions of food and fluid intake,
inspection of Figure 6.9 suggests that the activity counts during the daytime were lower when
fasting. Further work needs to be performed to clarify the reasons for this possible
discrepancy between objective and subjective measures of amounts of activity. Wrist
actimetry is normally a reliable indicator of general physical activity (Carvalho-Bos ef al.,
127
2003), but that there are some circumstances - if an activity is stressful, reqUIres large
amounts of isometric contraction, or involves large amounts of hand movements, for example
- where this parallelism between actimetry and subjective assessments fails (Waterhouse et
aI., 1 999b ). There is also the possibility that the subjective estimates might be affected by
fasting (Reilly and Waterhouse, 2007). The issue remains unresolved, there being a need for
detailed comparisons between subjective estimates of "physical activity" and objective
assessments by wrist actimetry in control and fasting conditions.
Wished-for physical (Figure 6.3) and mental activity (Figure 6.4) were both negatively
affected by fasting, a result found previously in the literature (Reilly and Waterhouse, 2007;
Waterhouse et al., 2008a, 2008b) as well as in previous chapters in this thesis. The time-of
day effects that were present (wishing for more mental activity and less physical activity as
the day progressed) are in accord with the literature on the subject (Reilly et al., 1997;
Waterhouse et al., 2001); the rise in mental activity is probably due to effects of "waking up"
and the fall in physical activity due to the onset of physical fatigue. It is predicted that both
variables would show a decline if measured later in the day, due to the combined effects of
increased time awake, general fatigue and preparations for sleep driven by the body clock.
Osmotic pressure (Figure 6.6) showed changes that were very similar to those reported in
chapters 3 and 5) and fully supportive of the hypotheses proposed in the Introduction to this
study. Thus, values were quite high and very similar in the three parts of the experiment on
rising, indicative of mild dehydration due to no fluid intake since suppertime. After this, the
values fell on the control day due to fluid restoration. On the day when breakfast only was
taken, values also fell initially by a similar amount (due to fluid intake) but then rose after
12:00 h due to fluid restriction. When fluid was not allowed (the fasting day), the osmolality
128
increased at 12:00 h above its rising value with a further rise by 16:00 h. Such results indicate
clearly that fluid restriction results in dehydration, the degree of which is quite marked by
16:00 h on the fasting day. Previous studies (Waterhouse et al., 2008a,2008b and Chapter 3)
have shown that this dehydration is normally combated in the evening by increased intakes of
fluid, particularly water and fruit juice which do not have diaphoretic or diuretic properties.
Since dehydration has a negative effect upon physical performance (Reilly and Waterhouse,
2007; Waterhouse, 2010), this would be expected in the present study.
In contrast, the performance at throwing darts (Figures 6.8, 6.9), both the scores achieved and
the number of misses, showed no effects of fasting. Moreover, there was no time-of-day
effects such as had been shown to exist in previous studies (Edwards et a/. , 2007, 2009).
There are several possible explanations for this result, and they will be discussed in chapter 7.
At this stage, it is only necessary to state that such a task, as performed in the current study,
appeared to be inadequate for assessing any decrement in performance that might have
existed. By contrast, such decrements were present when the effects of a bout of exercise
were considered (see below).
Exercise caused small falls in body weight (Figure 6.10), probably the result of sweating, to
remove excess body heat, but the rate of sweating was not measured. Even though the
changes did not depend significantly upon Day or Time of day, there is the suggestion that
the falls were greater on the control days than when fasting. Accepting that the urine
osmolality indicated that dehydration was present when fasting (Figure 6.6), such a reduced
rate of sweating would be predicted.
129
As predicted from a consideration of the urinary evidence for dehydration (above), perceived
exertion (RPE) following the bout of exercise showed negative effects of restricted food and
fluid intakes (Figure 6.14). The greater the fluid restriction (Fasting> Breakfast> Control),
the greater was the effort perceived to be, even though the exercise itself was of a constant
load. Moreover, RPE increased as the day progressed - that is, as the degree of dehydration
due to fluid restriction became more marked (compare the profiles of Figures 6.6 and 6.14).
Such results accord with the literature on the effects of dehydration (reviewed in Reilly and
Waterhouse, 2007; Waterhouse, 2010). RPE is also likely to rise if core temperature rises
more with exercise, as would be the case if sweating were inhibited by dehydration (see
above)
The bout of exercise caused rises in RER, lactate and heart rate, all of which would be
predicted from basic physiology. However, as found previously (Waterhouse el aI., 2009 and
Chapter 3), the effects of time of day and fasting were complex. The increase in RER (Figure
6.11) was greatest on control days, consonant with the view that glucose was a more
important substrate during exercise than on days with fasting. On days with normal food and
fluid intake (Control), glucose metabolism (from the food eaten) tends to increase during the
Course of the day; by the afternoon, glucose is the main substrate for metabolism. Therefore,
the switch to glucose metabolism produced by exercise is likely to be less marked in this
circumstance, and this might account for the decreased rise in RER produced by exercise at
16:00 h during the control part of the experiment (see Figure 6.11).
Exercise increased blood lactate levels (Figure 6.12) and this rise was greatest on the control
day. Again, given that glucose is likely to have been the main substrate on control days and
130
that fat metabolism would have played a more important role on fasting days, this would be
predicted.
Heart rate rose following exercise (Figure 6.13) and the size of this rise was proportional to
the amount of fasting. Since the amount of exercise did not change, these rises are an
objective indication of the "stress" caused by the bout of exercise. The stress can arise
directly, from restrictions to food intake (reducing energy stores) and fluid intake (causing
dehydration and reducing venous return, so requiring an increase in heart rate to maintain
blood pressure); it can also rise indirectly, due to a fall in motivation of the subject, any task
then being perceived as more difficult to perform. In support of this role of stress, the profiles
of Figures 6.13 and 6.l4 are very similar, objective (rise in heart rate) and subjective (RPE)
estimates of stress matching closely. It is widely reported that dehydration and lack of food
intake decrease physical and mental performance, cause a given activity to be more difficult
to achieve, and result in a workload being perceived as being more difficult (reviewed in
Reilly and Waterhouse, 2007, 2009; Waterhouse, 2010).
131
6.4.1. Conclusions
Taking all results together, it is concluded that restriction of food and fluid intakes for a
single day in a laboratory environment produces widespread effects upon the individual with
regard to subjective perceptions of daily activities, perceived workload when performing
exercise, and objective measures of "stress" and changes to metabolism produced by a bout
of exercise. These changes are associated with the amount of dehydration produced by the
restriction of fluid intake, as assessed from urine osmolality, and causal links are possible, a
possibility that was also considered when the correlations investigated in Chapter 5 were
discussed. For other variables, including actimetry and performance accuracy at throwing
darts, the effects of fasting were not as clear statistically, even though they also tended to
show deterioration later in the daytime.
Even though the changes that have been observed are very similar to those observed in field
studies of Ramadan (Waterhouse et a/., 2008a, 2008b, 2009 and Chapter 3), the field studies
suffered from an interpretive ambiguity. This ambiguity was that Ramadan is associated with
sleep loss as well as fasting. In the current study, sleep loss was avoided, and so the changes
observed can be attributed to effects of food and fluid restriction only. This is not to say that
sleep loss is without effect. There is much evidence that sleep loss causes performance
decrements (see reviews in Valdez et aI., 2008; Waterhouse el aI., 2001) and a study to
investigate the interaction between the decrements caused by sleep loss and fasting could be
the subject of further study.
132
Chapter 7
General Discussion, Conclusions, Future
Work and Implications
\~~
~t~ JMU
Liverpool John Moores University
7.1. General Aims
As indicated in Chapter 2 of the present thesis, the aim has been to build upon previous work
performed in the field (Waterhouse et aI., 2008a, 2008b). The following extract is taken
directly from the Conclusions section of the second paper, a field study performed in Libya
and comparing results with a similar study performed in the UK:
"We draw the following conclusions from our results:
1. Ramadan resulted in decreases in several types of daytime activity and increases in
fatigue and the frequency with which naps were taken in the first part of the daytime.
2. Based on food and fluid intake, there was evidence for preparing for the fasting period
during Ramadan, and strong evidence for changes after the end of the fast, at sunset.
These latter changes can be interpreted as "recuperation" from fasting, though social
factors and a general increase in activity were likely contributory factors.
3. Before sunrise and after sunset, there were changes during Ramadan in the
frequencies with which reasons for taking naps in the daytime were cited, as there
were in the frequencies of reasons for drinking or not drinking, and eating or not
eating. These changes meant that the links between fatigue and activity and between
fatigue and fluid and food intake were all altered in Ramadan.
4. Subjects become dehydrated during the daytime, but this was not reduced 10
menstruating females who drank during this time.,
134
5. There were several differences between results from the studies in the UK and Libya.
Some of these differences (in the amount of activity undertaken, for example) can be
interpreted to indicate conservation of energy during the daytime by the Libyan
subjects; other differences (in fluid and food intake and the reasons for this, for
example) suggest that there were cultural factors in preparing before sunrise for the
daytime fast and recovering from it after sunset.
These findings have been extended in two main ways. First, more measurements have been
made of mental and physical performance and of physiological variables. Second, laboratory
based studies using non-Muslim subjects and investigating only one day of fasting have been
used.
7.2. The Field Study
Subjective assessments of performance obtained in the current field study (Chapter 3) gave
results that were essentially the same as those obtained previously; subjective assessments
indicated that less mental and physical performance was carried out and wished for during
Ramadan. These findings validated the protocol, the subjects used and the measurements
made. The measurement of urine osmolality confirmed that the subjects became dehydrated
during the period of fasting, and the bout of exercise produced many physiological and
biochemical changes that differed during fasting from control conditions. That is, there was
clear evidence that exercise was felt to be more difficult in Ramadan and metabolic effects
were different from on control days. It is likely, but not proved, that the changes observed
resulted directly from the fasting (see Chapter 1).
Some of the conclusions were (taken from Chapter 3):
135
"In swnmary, Ramadan makes many demands upon those involved, and is responsible for
changes in sleep, daytime sleepiness, actual and desired behaviour, and physical
performance. The changes cause a decrease in both the amounts of daytime activity actually
performed and in the amounts desired. There is also evidence that a given bout of physical
performance at the end of the daytime fast places a greater burden on the body, and is
perceived as being more demanding than is the same bout of activity performed earlier in the
daytime. Individuals recuperate after sunset by eating and drinking more, and their intake of
fluid tends to exclude drinks which would promote further dehydration."
Other points arising from this field experiment will be discussed later, but one further point is
immediately relevant. Even though the investigation was a field study (insofar as the subjects
were practising Muslims taking part in Ramadan), the tests were carried out in a fully
equipped sports laboratory. It was clear that, without this special circumstance - that is, if it
had been necessary for the measurements to be made away from a laboratory - the protocol
would have been impracticable. In fact, it was such limitations associated with field studies
(Chapter 4, part I) that meant that later experiments were performed in the laboratory.
7.3. The Laboratory-based Studies
The two laboratory-based studies (Chapter 4, part II and Chapter 5) repeated many of the
measurements made in the field study but they differed in several respects: more measures of
mental and physical performance were made; only one day of fasting was considered (instead
of one month); and non-Muslim subjects were used. Many of the results, including the
development of dehydration and greater difficulty in performing the bout of exercise, were
very similar to those found in the field study. This implies not only that a one-day experiment
136
can give results that are relevant to studies of the effects of Ramadan but also that subjects
need not be practising Muslims. However, there were some results that differed from those
found previously and other that were unexpected.
One difference was that evidence of preparation for the time of fasting was less clear;
subjects did not all drink large amounts of fluid before the start of the fast (though there was
evidence of fluid and food replenishment after the end of the time of fasting). Another
difference was that daytime naps were taken far less frequently than found in the previous
work (Waterhouse et ale , 2008a, 2008b). Unexpected results included the observation that
many of the tests of mental and physical performance (the Stroop test, grip strength and
throwing darts) showed little or no negative change during fasting. This was particularly
surprising for the task of throwing darts since this has been used previously to investigate
successfully circadian changes and effects of time awake and sleep loss upon the accuracy of
performing this task (Edwards and Waterhouse, 2009). The explanation of these differences
from results obtained in the field studies and from expectations based upon measurements in
other studies is unknown, but possible reasons and ways to assess these will be considered in
the section on Further Work.
7.3.1. Separating the effects of sleep loss from fasting - the intervention study
Apart from the negative effects of fasting upon performance in a short bout of exercise, other
tests of mental and physical performance, though validated in other studies, showed very
little change in the present work. Several possible reasons exist for this: (I) insufficient
practice at the task before the experiment; (2) insufficient supervision while performing the
task; and (3) lack of sensitivity of the task. Items (l) and (2) could easily be remedied in
137
further studies but the other issue is more difficult, if only because a negative result
statistically (no change) could indicate a small (or non-existent) effect or too much variability
in the results. One possibility would be to measure accuracy at throwing darts, a task that has
been shown to be sensitive in previous studies involving sleep loss (Edwards et aI.,
2007,2009), at multiple stages during the course of Ramadan. Measurements could be
repeated at weekly intervals (see Waterhouse et aI., 2008a, 2008b), or more frequently, in
conditions which were strictly supervised and highly standardized, using subjects who had
practised the task until they had reached a performance plateau. These last conditions would
minimize within-subject variation and increase the chance of measuring small changes.
7.4. Further Work
7.4.1. Measurement of performance
Apart from the negative effects of fasting upon performance in a short bout of exercise, other
tests of mental and physical performance, though validated in other studies, showed very
little change in the present work. Several possible reasons exist for this: (1) insufficient
practice at the task before the experiment; (2) insufficient supervision while performing the
task; and (3) lack of sensitivity of the task. Items (1) and (2) could easily be remedied in
further studies but the other issue is more difficult, if only because a negative result
statistically (no change) could indicate a small (or non-existent) effect or too much variability
in the results. One possibility would be to measure accuracy at throwing darts, a task that has
been shown to be sensitive in previous studies involving sleep loss (Edwards et aI.,
2007,2009), at multiple stages during the course of Ramadan. Measurements could be
repeated at weekly intervals (see Waterhouse et at., 2008a, 2008b), or more frequently, in
conditions which were strictly supervised and highly standardized, using subjects who had
138
practised the task until they had reached a performance plateau. These last conditions would
minimize within-subject variation and increase the chance of measuring small changes.
7.4.2. Subjective vs. objective measurements of activity
While actimetry is an objective measure of movement, it does not enable types of movement
to be distinguished (Carvalho-Bos et af., 2003). Even though subjects report that they do less
and wish to do less when fasting, it is not clear whether this is, in fact, true, whether the same
types of task are performed but more slowly, or if different types of task are undertaken.
Observation of subjects and "scoring" them for the different types of activity they perform
(and the amount and speed of performing these activities) could be compared with
simultaneous measurements of actimetry from multiple sites (wrist, ankle, and back, for
example).
In the relevant studies perfonned so far (Waterhouse et al., 2008a, 2008b, 2009 and Chapters
3-5), one limitation has been that subjects have had commitments (whether work, study or
child-rearing, for example) and this will have influenced their activity patterns and restricted
their option to be less active. Using subjects who have none of the above commitments would
overcome this difficulty. Such subjects could be investigated in short studies performed in the
laboratory as well as in longer field studies during Ramadan.
7.4.3. Role of naps
In the same way as daily commitments might influence activity, even though changes in the
length of sleep at night might increase daytime sleepiness, the subjects are often not free to
nap during the daytime. Again, this is the case when the majority of the subjects are students
139
or workers with work schedules to keep. To investigate the true "cost" of loss of sleep at
night, a similar suggestion to that made for measuring daytime activities in the absence of
commitments is offered. It is suggested that subjects should have little structured
commitments but rather be free to do what they wished when they wished to do it (see
Waterhouse et a/., 2005). It is predicted that this protocol would result in the frequency of
daytime naps on fasting days being greater than that on control days, this difference better
reflecting the "stress" caused by sleep loss at night in Ramadan. Moreover, subjective
estimates of sleep are inferior to objective measures (polysornnography) and this latter
method could also investigate sleep architecture at night as well as during daytime naps
(Bahammam, 2003, 2004: Roky et al., 2003; Margolis and Reed, 2004).
7.4.4. Possible interaction between sleep loss and fasting
As discussed in Chapter 6, many of the negative results observed in Ramadan and in the
laboratory-based studies of Chapters 3-5 seem to be due to fasting rather than sleep loss since
they were replicated when sleep was controlled (Chapter 6). Even so, the intervention study
could be modified in such a way that sleep loss is manipulated and the amount of fasting is
standardized (using a protocol based on that used for Chapter 6). It would be predicted that, if
sleep loss itself does not contribute significantly to the negative effects observed in Ramadan,
changing the amount of sleep lost would be without effect. An alternative hypothesis is that
sleep loss and fasting together combine to produce decrements that are greater than those due
to either intervention alone. Results from the proposed protocol, combined with those from
Chapter 6, could be used to investigate this alternative hypothesis.
It is interesting to note that many athletes delay training until the evening, after the fast has
ended (Wilson et al., 2009). Moreover, some can delay retiring and rising times so that the
140
duration of daytime fasting is curtailed. (In this respect they are showing a more extreme
version of the delayed habits shown by the subjects in the field study, Chapter 3). The
detailed nature of their sleep patterns and their circadian rhythms of performance and
metabolism are all areas that deserve further investigation.
7.4.5. Subjects' experience
The results from the first field study of this thesis (Chapter 3) indicated that sleep times were
delayed in Ramadan, subjects not only retiring later but also rising later; indeed, total sleep
time was increased, unlike changes observed in the first two field studies (Waterhouse et a/. ,
2008a, 2008b) and in general (Reilly and Waterhouse, 2007). This might reflect the facts that,
unlike the case in the first two field studies, the individuals were not independent, still living
with their parents. Also, the laboratory-based studies (Chapter 4, part II and Chapter 5)
indicated that non-Muslims, who had not previously fasted in the daytime, made less
preparation for the fast. These results indicate that a subject's experience of the demands of
fasting is an important factor in studies such as these. This issue could be tested as follows.
Subjects would be required to undergo a series of fasting days, either sequentially or at
weekly intervals, for example. Both Muslim (experienced in the demands of fasting) and non
Muslim subjects (initially inexperienced) would take part separately, and the results would be
compared. It is predicted that any differences with regard to preparation for fasting would
disappear during the course of the experiment as experience was gained by the non-Muslims.
7.4.6. Metabolism
The results from all four studies indicate that fasting causes a bout of exercise to seem more
difficult to perform. Fasting also alters metabolism at rest and following the exercise. Many
141
other aspects of metabolism could be investigated, including hormones associated with the
short-term (insulin and cortisol, for example) and long-term (leptin, for example) metabolism
of food. Further, although the studies have shown that food and fluid intakes before and after
fasting can be altered, more detailed information on the type and amounts of food and fluid
taken in would be valuable; the present questionnaires are only a first approach to this whole
problem.
7.5. Concluding Comments and Implications of the Findings
In my transfer report, I wrote: "Taken together, the four studies, together with the results
from the previous two field studies (Waterhouse et aI., 2008a, 2008b) will enable a far more
detailed understanding of the changes produced by fasting as undertaken in Ramadan to be
understood. "
I believe that the results from the present studies have added to our knowledge of the effects
of fasting upon several aspects of physiology and biochemistry. The results have also raised
some problems relating to differences that might arise due to the type of measurement made,
the subjects used and the detailed protocol employed. The further experiments, described
above, should clarify some of these issues.
The findings have several implications for those undertaking fasting, particularly for
extended periods of time during Ramadan.
142
7.5.1. Implications of the findings
The present findings have several implications for those undertaking fasting, particularly for
extended periods of time as during Ramadan. As indicated in the literature survey (Chapter
2), there is some evidence for decreased performance ability during Ramadan but the effects
upon routine daily tasks seem to be comparatively slight. By contrast, when a greater degree
of physical exertion is required and for a more extended period of time (as in sports training,
for example), the negative effects seem to be more marked (Reilly and Waterhouse, 2007).
However, most studies have considered changes on a weekly basis rather than during the
course of the waking day. The present studies have investigated changes during the weeks of
Ramadan and have confirmed that these are not progressive, changes during the fourth week
of Ramadan not being significantly different from those in the first week. Adjustment to the
demands of Ramadan is rapid, therefore, probably reflecting the fact that the vast majority of
Muslims will have experienced the demands of Ramadan on previous occasions.
What is new about this work is that decrements during the course of the waking day have
been investigated, and these have been found to be more marked towards the end of the
period of fasting. These decrements include: SUbjective estimates of the amount of physical
activity actually performed and of the amount of work that individuals wish to perform; and
objective estimates of responses to exercise, indicating that it is more "stressful" at the end of
a period of fasting. There is also evidence suggesting that objective measures of activity
decrease and performance at tasks involving neuromuscular co-ordination deteriorates
towards the end of the fasting day. This general deterioration is associated with the
progressive amount of dehydration and loss of energy stores that occur during fasting.
143
As a result of these changes, the individual is more disadvantaged at the end of the fasting
day than in the morning. It is predicted from this result that road traffic accidents, for
example (see Roky et aI., 2004), will be increased more when individuals are returning home
at the end of their work period compared with going to work in the morning. The findings
also suggest that tasks that are physically demanding (and also tasks that are mentally
demanding, since mental performance is also worse later in the day when fasting) should be
perfonned earlier in the daytime.
An alternative to performing such tasks earlier in the daytime is to perform them after
breaking the fast, having drunk and eaten and so having begun to replenish lost stores of body
fluid and energy. In support of this suggestion, some training sessions are conducted after
sunset in Ramadan (Wilson et al., 2009). However, whilst delaying these sessions might be
acceptable in countries where the majority of team members are Muslim, it is unlikely to be
acceptable when only a minority ofthe team undertakes fasting in Ramadan.
144
Chapter8
References
't~J
~t~ JMU
Liverpool John Moores University
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164
Chapter 9
Appendices
\~J
~t~ JMU
Liverpool John Moores University
Appendix 3.1. Consent Form
LIVERPOOL JOHN MOORES UNIVERSITY CONSENT FORM
Title: The effects of fasting fo r a single day and during Ramadan upon sleep and waki ng performance
Researchers : Hadhom Alabed Supervisor: Jim Waterhouse
Faculty: School of Sport and Exercise Sciences
1. I confirm that I have read and understand the information provided for the above study. I have had the opportunity to consider the information , ask questions and have had these answered satisfactorily.
2. I understand that my participation is voluntary and that I am free to withdraw at any time, without giving a reason and that this will not affect my legal rights .
3. I understand that any personal information collected during the study will be anonymised and remain confidential.
4. I agree to take part in the above study.
Name of Participant
Name of Researcher
Name of Person taking consent (if different from researcher)
Date
Date
Date
166
Signature
Signature
Signature
D D D D
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172
Appendix 4.1. Questionnaire given at 09:00 h. For more details, see text.
A. SLEEP: 1 Est' t d' f' . . lma e tIme 0 retIrIng ................... . 2 Est' t d' f .. . lma e tIme 0 rIsmg .................... .
(For questions 3a-3e, place a mark on the lines to indicate your responses):
3. Last night's sleep, when compared with normal:
a. How easily did you get to sleep?
-5 ------------------------------------------ 0 -------------------------------------- ~5 much less
easily
b. What time did you get to sleep?
normal much more easily
-5 ------------------------------------------ 0 -------------------------------------- ~5 earlier normal later
c, How well did you sleep? -5 -------------------------__________________ 0 --------------------------------------- ~5 more waking
episodes normal fewer waking
episodes
d. What was your waking time?
-5 ------------------------------------------ 0 -------------------------------------- ~5 earlier normal later
e. How alert did you feel 30 min after rising?
-5 ------------------------------------------ 0 -------------------------------------- ~5 less normal more
f. Did you eat or drink anything in the hour before going to bed? (Ring one) 1. No 2. A drink only 3. A snack 4. A small meal.
g. If you ate or drank anything, do you think it helped you sleep? (Ring one) 1. No 2. A little 3. A lot
173
B.DRINK:
4. Did you drink anything since waking time? (Ring one answer) YES NO
If you answered YES, go to question 5. If you answered NO, go to question 8.
5. How much did you drink? (Ring as many answers as apply) a. one sip or mouthful b. less than one glass or cupful c. one glass or cupful d. more than one glass or cupful
6. What did you drink? (Ring as many answers as apply) a water b. tea or coffee c. fruit juice d. fizzy drink e. milk
7. Why did you drink? (Ring as many answers as apply) a. I felt thirsty b. I was with a friend and being sociable c. For health reasons (including having my period)
Go to Section C, FOOD
8. Why did you NOT drink? (Ring as many answers as apply) a. I did not feel thirsty h. I never drink at this time c. I was too busy d. I am not allowed to drink during this time
C. FOOD:
9. Did you eat anything during this time? (Ring one answer) YES NO
If you answered YES, go to question 10. If you answered NO, go to question 12.
10. How much did you eat? (Ring one answer) a. snack b. small meal c. medium sized meal d. large meal
174
11. Why did you eat? (Ring as many answers as apply) a. I felt hungry b. I was being sociable c. I was preparing for times when I would not eat d. for health reasons (including having my period)
Go to Section D, Activities and Feelings. 12. Why did you not eat? (Ring as many answer as apply) a. I did not feel hungry b. I never eat at this time c. I was too busy d. I am not allowed to eat during this time
D. ACTIVITIES AND FEELINGS: The answers to questions 13 - 18 are a number from 0 to 4, where:
o means "not at all" 1 means "slightly" 2 means "moderately" 3 means "quite a lot"
and 4 means "very much"
13. How physically active have you been? (ANSWER 0 - 4) .... .
14. How mentally active have you been? (ANSWER 0 - 4) .... .
15. How socially active have you been? (ANSWER 0 - 4) .... .
16. How sleepy do you now feel? (ANSWER 0 - 4) .....
17. How able to perform physical tasks do you now feel? (ANSWER 0 - 4) .... .
18. How able to perform mental tasks do you now feel? (ANSWER 0 - 4) .... .
175
Appendix 4.2.VSection A of questionnaire given at 12:00,17:00 and 21:00 h. For more details, see text.
A. SLEEP: 1. Did you sleep during this time? (Ring one answer)
YES NO
If you answered YES, go to question 2. If you answered NO, go to question 4.
2. About how long did you sleep? (answer in hours) .......... .
3. Why did you sleep? (Ring as many answers as apply) a. I felt tired b. I was bored c. I wanted to catch up on lost sleep
Go to question Section B, DRINK
4. Why did you NOT sleep? (Ring as many answers as apply) a. I did not feel tired h. I never do sleep at this time c. I was too busy d. I am not allowed to sleep
176
Appendix 5.1. Accuracy of throwing darts
Hand-eye coordination test 20 shots Dominant hand Performance Total score Average score Distance (2.37m)
177
Appendix 6.1. Gas AnaJysis Using the DougJas Bags
C) HO\N to Construct the Hans Rudolph Mouth Piece for Expired Gas Analysis
Step I) Collect the individual pieces.
Top & • - I' } I. e
Mouth piece connector
Gas hose connector -
Step 2) Connect Valve 2 t:o tb.e bot.tom. of the
MiddJe connector '",!Ie: .... S5ilIii
Step 3) Sere"" together the middle connector to the gas hose connector ."..,ith va_lve 2 in bet:w-cen thCDl . You must ensure that the gas can floW' in a dovvn'WlH"ds direction!
Step 4) Place valve I onto the top o£the tnidcUe connector
.. _ 1,0. · .,
Valve I
Middle connector
Valve 2
Step S) Sere"" together the top piece to t.h .c middJe connecto .... 'W'ith valve .1 in betw'een them. Again you must ensure that the gas can floW' in a do~vvard5 direction I
Step 6) Screvv the mouth piece connector to the middle connection. piece
Step 7) Collect the mouthpiece and gas hose ready f"or connection
Step g) Connect the mouthpiece and the gas hose to complete the setup.
Sehool or Sport .nd Exercl ... Sel .... e .. - Liverpool Joh .. Moores U .. lverslty
178
o _ is using the Douglas Bags .- ,
Step I . ) Collect all the relevant equipment
i.e . Dougl3S bags, mouthpiece, hoses, nose c lips)
Step 2,)Record the following me ... rement. before yo ... t.rt: -
Ambient temperature. HumidIty and Darametric press .. re (mmHg) (:tee .heet 4)
Step 3 .) Collectin g Expired gBS in a Douglas Bag
:.,."'. .i .~ 't' .~ _~ ~.I". or: ~ ___
~ .. . ~-: .. ~-.~ ~ ...
-Evacu ate a ll the gas from the bags before you start
-En sure a ll valves are closed so DO
air can get into or out of the bags
-En sure Mouthpiece and hose lIir securely fitted to the Douglas bags
-Attach the mouthpiece to the su bject and fit the nose clip
-Open the valve on the Douglas Bag to start expired gas collection. Duration sbould be I minute.
-Close v alve when finished
- _ . ~~i+ ," -- -::
~'.' .' ... :. " .. :~~
i', . .a.'~ ' .= , •• ",. , :.'~.";-~: ' -'"' ~ '"
S chool of S port lind E xercise Science - Liv~rpeol .John Moores U nIv ersi ty
179
Step 4 .) Calibrate the Gas Ana lyser (Servo max)
-Turn on pumps to allow a reading for ambient conditions ~ O 2 = 20.9 , CO, = 0 .04 You may need to tweak the value s to get an accurate result
-Fill a glls bag with clllibrlltion go. and run it through the an alyser ~ CIII gas = O 2 = 16 .0, CO, = 4 .0
Step 5 .) Analysing the gas with the Gas Ana lyser (Servomax)
-Attach the Douglas Bag tubes to the connection a t the back of the analyser
-Open the va lves thllt correspond with the Douglas Bag a nd tum pumps on
-Wait for 0/.02 and %C02 to stabilise and record the values
.!~ t ''''
-Close the valves and disconnect from the IInslyser
® Measuring Minute Ventilation and Expired Gas
Step 6) Attach Dou"I85 Sag to the Harva,-d Dry Gas M_eter
Temperature from the Douglas Bags t .. &2 I
. - <~ . -.~ ...... " -~>.- ~
Step 10) Tum on the Harvard Dry Ga. Meter
--....... ~~, -
Step 7) Reset volume Dlcter dial to zero Step I I) Record the volume and gas temper-Bture 'When the bag is emptied
Step 8) Read expired gas tempe ... atur e from the top reading and room temperature front the bottom reading
~-- ~ .. . ..""'t t Step 9) Open tl.., Douglas Bag valve.
For the appropriatc Douglas Bag
Step 13 ) Reset dill1 to zero • .fier use .
Step 12) Close Douglas B"g. turn off Harvard Dry Ga. Metcr
~ . ·= ~ l .! DC, t ~ 4
.; ~ . -.
II~ St~p J 4) 'V.ph ,II pi,,"' n(NJMlpment YOM hlye VIed ia the Millon ,ol.tt •• nrovided - i c. mouthoiece. "Ole clln. hoaC'
S eh-ool of S JMr1. .nd Exerci.e Sd."ce - Liverpool John Moore8 U .. iversity
180
w
CD How to Measure Barametric Pressure (mmHg)
Barometer
Check that the mercury is Just touch the white knob.
If the mercury is too h igh or too low, twist the screw to increase or decreases the mercury until it touches.
181
Then simply read off the results in either mmHg or mbar
Appendix 6.2. Blood lactate
Lactate Pro Meter Set
Speedy measurements and simple operation - Blood Lactate Testing
Insert the test strip into the strip inlet of
the meter.
Collection of the blood .
182
Blood is automatically aspirated and measurement
begins.
The measurement result is displayed
in 60 seconds
Appendix 6.3. BORG SCALE (Rating of Perceived Exertion)
6- No Exertion at all
7- Extremely Light
8-
9- Very Light
10-
11- Light
12-
13- Somewhat Hart
14-
IS-Hart
16-
17-Very Hart
18-
19-Extremely Hart
20- Maximal Exertion
183
